Molim te, namjesti alarm za šest, jer sutra moramo krenuti rano.

Because moliti takes a direct object, so the pronoun has to be in the accusative case.

• te = you (accusative, informal singular)
• ti = to/for you (dative), so it would be wrong here

As a fixed expression, Molim te means please when speaking to one person informally.

Compare:

• Molim te = Please / I’m asking you
• Molim vas = Please (formal or plural)

Namjesti is the imperative form, meaning set! or adjust!, addressed to one person informally.

It comes from the verb namjestiti, which means to set, adjust, fix into place.

So:

• namjestiti = to set
• namjesti! = set!

In this sentence, it is used because the speaker is asking someone to do one specific action: set the alarm.

This is about aspect, which is very important in Croatian.

• namjestiti = perfective: one completed action
• namještati = imperfective: ongoing, repeated, or habitual action

Here, the speaker wants one completed result: the alarm should be set. That is why namjestiti is natural.

So:

• Namjesti alarm = Set the alarm
• Namještaj alarm would sound more like keep adjusting the alarm or set it repeatedly, which does not fit as well here.

Even though alarm is the direct object of namjesti, it stays alarm because it is a masculine inanimate noun.

In Croatian, masculine inanimate nouns usually have:

• nominative singular = accusative singular

So:

• dictionary form: alarm
• direct object form: alarm

That is why you get:

• namjesti alarm

If it were a masculine animate noun, the accusative would usually change.

Yes. Budilica is also possible, and many learners will meet both words.

The difference is roughly this:

• alarm = alarm, often especially a phone alarm
• budilica = alarm clock, or sometimes the wake-up alarm itself

So both of these can work:

• Namjesti alarm za šest.
• Namjesti budilicu za šest.

In the second sentence, budilicu is accusative singular of budilica.

Because Croatian often uses za + time when talking about setting something for a certain time.

So:

• namjesti alarm za šest = set the alarm for six
• u šest usually means at six, describing when something happens

Compare:

• Namjesti alarm za šest. = Set the alarm for six.
• Budimo se u šest. = We wake up at six.

So za šest is the natural choice when the time is the target setting.

Here za takes the accusative.

So in za šest, šest is accusative. However, with many numbers, the form looks the same as the nominative, so you do not see a visible change.

That means:

• nominative: šest
• accusative: šest

So the case is there grammatically, even though the word itself does not change shape.

In standard Croatian, a comma is normally used before jer when it introduces a subordinate clause.

Here:

• main clause: Molim te, namjesti alarm za šest
• subordinate clause: jer sutra moramo krenuti rano

So the comma separates:

• the request from
• the reason for the request

This is standard punctuation in Croatian.

In standard Croatian, after morati (must, have to), the usual pattern is:

• morati + infinitive

So:

• moramo krenuti = we have to leave/start

This is the standard Croatian structure.

A structure with da + present tense is much less typical of standard Croatian and is more associated with other South Slavic varieties or regional speech.

So for standard Croatian, moramo krenuti is the best model to learn.

Krenuti means to set off, start moving, leave, and it is a very common verb in sentences like this.

It is also perfective, which fits well because the speaker is talking about one concrete action in the future: we have to leave.

Other verbs are possible in some contexts, but krenuti is very natural for:

• leaving home
• starting a trip
• setting off early

So:

• sutra moramo krenuti rano = tomorrow we have to leave early

Because rano is an adverb, and here it modifies the verb krenuti.

It answers the question How do we have to leave?

• rano = early

Croatian uses:

• ran = adjective, like early in an early train
• rano = adverb, like leave early

So in this sentence, only rano works naturally.

No, Croatian word order is fairly flexible.

The version in the sentence is completely natural:

• jer sutra moramo krenuti rano

But you may also hear:

• jer sutra moramo rano krenuti

Both are correct. The difference is mostly about rhythm or slight emphasis.

A useful general idea:

• rano krenuti can sound a bit more tightly connected as leave early
• krenuti rano is also very normal

So learners should know that Croatian often allows more than one natural word order.

You would change both the please phrase and the imperative form:

• informal singular: Molim te, namjesti alarm za šest...
• formal or plural: Molim vas, namjestite alarm za šest...

So the full formal/plural version is:

Molim vas, namjestite alarm za šest, jer sutra moramo krenuti rano.

Changes:

• te → vas
• namjesti → namjestite