Learn Hardcore Greek: Βάζω αγγλικούς υπότιτλους όταν βλέπω ταινία, αλλά στα ελληνικά προτιμώ ελληνικούς υπότιτλους. - I put English subtitles when I watch a movie, but in Greek I prefer Greek subtitles.

ανοίγω τους υπότιτλους – I turn on the subtitles (more literally about pressing a button)
έχω υπότιτλους – I have subtitles (focuses on their presence, not the act of choosing/adding them)

Why is it αγγλικούς υπότιτλους and not just αγγλικά?

Because αγγλικούς is an adjective that must agree with υπότιτλους in gender, number, and case:

υπότιτλος (subtitle) is masculine, singular in the dictionary form.
Here we have υπότιτλους (accusative plural masculine) as the direct object.
The adjective αγγλικός must match that, so it becomes αγγλικούς (accusative plural masculine).

So we say:

αγγλικούς υπότιτλους = English subtitles

If you say simply αγγλικά, that usually means the English language (neuter plural) and not English subtitles.

Why is υπότιτλους in the accusative case?

Because υπότιτλους is the direct object of the verbs:

Βάζω αγγλικούς υπότιτλους – I put English subtitles.
προτιμώ ελληνικούς υπότιτλους – I prefer Greek subtitles.

In Greek, direct objects of transitive verbs appear in the accusative case.
That’s why both αγγλικούς and υπότιτλους (and later ελληνικούς υπότιτλους) are in the accusative plural masculine.

Why is there no article: αγγλικούς υπότιτλους instead of τους αγγλικούς υπότιτλους?

In Greek, you don’t always need the article with plural nouns when you talk about things in a general or indefinite way.

Here, αγγλικούς υπότιτλους means:

subtitles of that type in general
not some specific, known set of subtitles.

If the context were more specific, you could indeed say:

Βάζω τους αγγλικούς υπότιτλους. – I put on the English subtitles (the ones we both know about, e.g. on this film).

So:

without article = more general / indefinite
with article = more specific / known set

In this sentence the generic meaning (“I use English subtitles in general”) fits better, so the article is dropped.

Why is there no article with ταινία: όταν βλέπω ταινία instead of όταν βλέπω μια ταινία?

The phrase βλέπω ταινία (literally I watch film) is used to talk about the activity in general:

όταν βλέπω ταινία – when I’m watching a movie / when I watch movies (in general)

You would use an article when you mean one specific instance:

όταν βλέπω μια ταινία – when I watch a (particular) movie
όταν βλέπω την ταινία – when I watch the movie (a specific one we both know)

For habitual/general statements, Greek often omits the article with certain singular count nouns:

πίνω καφέ – I drink coffee
παίζω ποδόσφαιρο – I play football

Similarly βλέπω ταινία here describes a habitual situation: whenever I watch a movie.

Why is it στα ελληνικά but αγγλικούς υπότιτλους / ελληνικούς υπότιτλους? Why different forms for “Greek” and “English”?

You have two different uses of these adjectives:

As language names:
- στα ελληνικά = in Greek (language)
- Here ελληνικά is a neuter plural adjective used as a noun meaning “Greek language”.
- The preposition σε
  - article τα → στα
    - ελληνικά.
As normal adjectives modifying a noun:
- αγγλικούς υπότιτλους – English subtitles
- ελληνικούς υπότιτλους – Greek subtitles
  Here αγγλικούς / ελληνικούς are masculine plural accusative adjectives agreeing with υπότιτλους.

So:

στα ελληνικά – in Greek (language)
ελληνικούς υπότιτλους – Greek subtitles

They are the same adjective (ελληνικός) but used in different grammatical roles and cases.

Why is ελληνικά not capitalized in στα ελληνικά?

In modern Greek:

Languages written as adjectives are not capitalized:
- τα ελληνικά, τα αγγλικά, τα γαλλικά
Nationality words (proper adjectives for people, cultures) are capitalized:
- Έλληνας, Ελληνίδα, Αγγλίδα, Γάλλος

So στα ελληνικά is correctly lowercase, because it refers to the Greek language, not to Greek people or the Greek nation as a proper name.

Why is there no εγώ in the sentence? How do we know it means “I”?

Modern Greek is a pro-drop language: subject pronouns (like εγώ, “I”) are often omitted because the verb ending already shows the person.

βάζω – I put
βλέπω – I see / I watch
προτιμώ – I prefer

All of these are 1st person singular forms, so the subject is clearly “I”.

You could say:

Εγώ βάζω αγγλικούς υπότιτλους…

but that would usually add extra emphasis, like “I (as opposed to others) put English subtitles…”

Why is the present tense used: Βάζω, βλέπω, προτιμώ? Does it mean “I am doing it now” or “I usually do it”?

In Greek, the present tense (ενεστώτας) can express both:

An action happening now
A habitual / repeated action

Here the context is clearly habitual:

Βάζω αγγλικούς υπότιτλους όταν βλέπω ταινία…
→ I put English subtitles when I watch a movie…
= I usually / generally do this whenever I watch a movie.

So the Greek present here is like the English simple present describing habits.

Could we also say προτιμάω instead of προτιμώ? Is there a difference?

Yes, both forms exist:

προτιμώ
προτιμάω

They are equivalent in meaning: I prefer.

προτιμώ is a bit more common and slightly more formal/standard.
προτιμάω often sounds a bit more colloquial or spoken.

In this sentence, either is grammatically fine:

…στα ελληνικά προτιμώ ελληνικούς υπότιτλους.
…στα ελληνικά προτιμάω ελληνικούς υπότιτλους.

Why is the word order αγγλικούς υπότιτλους and ελληνικούς υπότιτλους? Can the adjective come after the noun?

The default (and most common) word order in Greek is:

adjective + noun
- αγγλικούς υπότιτλους
- ελληνικούς υπότιτλους

You can place the adjective after the noun, but it usually sounds:

more emphatic,
more poetic, or
sometimes a bit marked in everyday speech.

For example:

υπότιτλους αγγλικούς – subtitles that are English (emphasis on “English”)
υπότιτλους ελληνικούς – subtitles that are Greek

In normal, neutral speech, αγγλικούς υπότιτλους / ελληνικούς υπότιτλους is what you would typically use.

What exactly does όταν βλέπω ταινία imply? Is it “whenever I watch a movie” or “when I’m watching a movie (right now)”?

The phrase όταν βλέπω ταινία is a time clause with όταν (= when/whenever) plus the present tense, and here it expresses a repeated / habitual situation:

όταν βλέπω ταινία ≈ whenever I watch a movie / when I watch movies (in general)

If you wanted to talk about a specific situation going on now, you would usually give more context:

Τώρα που βλέπω ταινία, βάζω αγγλικούς υπότιτλους.
– Now that I’m watching a movie, I’m putting English subtitles on.

In the original sentence, everything points to a general habit, not a single event.