Learn Hardcore Swedish: Han glömmer ibland sitt lösenord när han ska logga in och skriva in det. - He sometimes forgets his password when he is going to log in and enter it.

it would normally be understood as “He sometimes forgets his (another man’s) password,” i.e. the password belonging to some other male person already mentioned in the context.

Why is it sitt and not sin?

The form of the reflexive possessive agrees with the grammatical gender and number of the noun it describes, not with the person:

sin – for en-words (common gender), singular
sitt – for ett-words (neuter), singular
sina – for plural nouns

The noun lösenord is an ett-word: ett lösenord.
Therefore the correct form is sitt lösenord, not sin lösenord.

Why is there a det at the end (skriva in det)? Can you leave it out?

Det is the object pronoun referring back to lösenord:

lösenord is an ett-word → the corresponding pronoun is det.

So:

… logga in och skriva in det
≈ “… log in and type it in.”

In Swedish you normally cannot just drop an object pronoun the way English sometimes can. You either:

Repeat the noun:
- … logga in och skriva in sitt lösenord.
Or use a pronoun:
- … logga in och skriva in det.

Leaving it out entirely (… logga in och skriva in) sounds incomplete and unnatural here, because skriva in almost always needs something that you are entering (a code, a name, a password, etc.).

Why is it det and not den at the end?

Swedish third-person singular pronouns agree with the grammatical gender of the noun:

den – for en-words
det – for ett-words

The noun lösenord is an ett-word (ett lösenord).
Therefore, the correct pronoun is det:

Han glömmer ibland sitt lösenord … skriva in det.

If the noun had been an en-word, you would use den, e.g.:

Han glömmer ibland sin kod och kan inte skriva in den.
(“kod” is an en-word.)

What is the difference between logga in and skriva in here?

They describe two separate actions:

logga in = to log in (perform the login process)
– This is the whole action of accessing an account/system.
skriva in = to type in / enter (by writing)
– This focuses on the specific act of typing something into a field.

So the sequence is:

He is going to log in (ska logga in).
As part of that, he has to type in the password (skriva in det).

That is why both verbs can appear together: they describe the overall action (logging in) plus a specific step in that action (typing the password).

Why is ska used before logga in? Could it just be han loggar in?

Ska here functions as an auxiliary that expresses intention or a planned/near‑future action:

när han ska logga in ≈ “when he is going to log in / when he is about to log in”

If you say:

Han glömmer ibland sitt lösenord när han loggar in …

this sounds more like a general present-time situation (“when he logs in”), which is also understandable, but ska emphasizes the idea of an upcoming step he’s about to perform.

Both are grammatically correct, but:

när han ska logga in – very natural when describing what happens right when he is about to log in.
när han loggar in – more neutral general present.

Also note: after ska, you use the bare infinitive (logga), without att:

ska logga (not ska att logga)

Can ska mean “must” or “should” here, like obligation?

In Swedish, ska has several common uses:

Future / intention / plan
- Jag ska åka hem. – “I’m going to go home.”
Obligation / command
- Du ska göra läxan. – “You must/shall do your homework.”

In när han ska logga in, ska expresses an upcoming or intended action, not a strong obligation. It’s more like:

“when he is going to log in”
“when he’s about to log in”

Context decides whether ska feels more like “going to” or “must/should”. Here it clearly fits the “going to” reading.

Why is it glömmer (present tense) even though it describes a habitual action like “sometimes forgets”?

Swedish uses the present tense for:

actions happening right now
repeated/habitual actions
general truths

So:

Han glömmer ibland sitt lösenord …
literally “He forgets his password sometimes …”

In English we prefer “He sometimes forgets …”, but grammatically that is also present tense (“forgets” is simple present). So the Swedish present tense matches the English simple present here and is the normal way to talk about habitual actions.

Why is ibland placed after glömmer? Could it be somewhere else?

Ibland is an adverb meaning “sometimes”, and word order is relatively flexible, but with different emphasis:

Han glömmer ibland sitt lösenord …
– Very natural, neutral word order. Ibland comes after the verb.
Ibland glömmer han sitt lösenord …
– Also very common. Placing ibland first emphasizes “Sometimes…” as the starting point of the sentence.
Han glömmer sitt lösenord ibland …
– Also possible; ibland at the end feels a bit like an afterthought or looser style.

All three are grammatically correct. The given sentence (Han glömmer ibland sitt lösenord …) is a very typical pattern: Subject – Verb – Frequency adverb – Object.

Why is it när han ska logga in and not när ska han logga in?

The reason is that när here introduces a subordinate clause, not a question.

När han ska logga in …
– “When he is going to log in …” (subordinate clause, part of a larger sentence)

In Swedish:

Main clauses: verb is normally in second position (V2).
- När ska han logga in? – “When is he going to log in?” (a real question)
Subordinate clauses (starting with words like när, att, eftersom, om): the subject usually comes before the verb.
- … när han ska logga in … – “when he is going to log in…”

So the pattern here:

Han glömmer ibland sitt lösenord (main clause)
när han ska logga in och skriva in det (subordinate clause)

In subordinate clauses, you do not invert han and ska.

What is special about the noun lösenord (gender, plural, etc.)?

Lösenord has a couple of features that can be confusing:

It is an ett-word (neuter):
- ett lösenord – a password
- lösenordet – the password
The plural is the same as the singular in the indefinite form:
- flera lösenord – several passwords
- lösenorden – the passwords (definite plural)

This is why you see:

sitt lösenord (using sitt and det, both neuter forms)
and not sin lösenord / den.

Understanding that lösenord is neuter explains the pronoun choices in the sentence.