Det ser ud til, at adgangskoden er ændret.

It is a fixed expression meaning it seems or it appears.

So in this sentence, Det ser ud til, at ... works much like English It seems that ...

Try not to translate it word for word. Literally, the pieces look like it looks out to, but that is not how Danish speakers understand it. As a chunk, it simply means it seems / it looks like.

Here, det is a dummy subject, just like English it in It seems that ...

It does not refer to a specific thing. It is there because Danish, like English, usually wants a subject in this kind of sentence.

So:

• Det ser ud til, at ... = It seems that ...

The det is grammatical, not really meaningful on its own.

Because they do different jobs.

• ser ud til is the fixed expression meaning seems / appears
• at introduces the following clause: that ...

So the structure is:

• Det ser ud til, at + clause

Here the clause is:

• adgangskoden er ændret

You will also see ser ud til followed by an infinitive:

• Det ser ud til at virke. = It seems to work.

So:

• til belongs to the expression
• at introduces what follows

The basic noun is en adgangskode, which means a password.

It is a compound noun:

• adgang = access
• kode = code

So literally it is access code, which is the standard Danish way to say password.

The form adgangskoden means the password.
That final -n is the definite ending.

A useful pattern:

• en kode = a code
• koden = the code

Many common-gender nouns ending in unstressed -e take -n in the definite singular.

Yes. In standard Danish, adgangskode is the normal and very common word for a login password.

A few notes:

• adgangskode = password
• kodeord usually means code word, not the usual IT word for a password
• English password may also be understood in tech contexts, but adgangskode is the standard Danish choice

So this sentence sounds natural and normal.

Because er ændret describes the password as being in a changed state, or says that it has been changed.

• er = is
• ændret = changed

Together, er ændret often corresponds to English has been changed or is changed, depending on context.

By contrast, har ændret usually means has changed or has changed something, and it normally needs a subject that is doing the action.

Compare:

• Adgangskoden er ændret. = The password has been changed.
• Nogen har ændret adgangskoden. = Someone has changed the password.

So in your sentence, er ændret is the natural choice.

Grammatically, the finite verb er is present tense. But the whole expression refers to the result of an earlier action.

So the idea is:

• right now, it seems that the password is in a changed state
• the changing itself happened before now

That is why English often translates this most naturally as:

• The password seems to have been changed
• or It looks like the password has been changed

So it is present in form, but it points to a completed change with present relevance.

Because at introduces a subordinate clause.

In Danish, main clauses and subordinate clauses do not always behave the same way. Danish main clauses are famous for verb-second word order, but subordinate clauses are different.

In this sentence, the clause after at is:

• adgangskoden er ændret

That is a normal subordinate-clause pattern: subject + verb + complement.

You can see the difference more clearly when an adverb is added:

• Main clause: Adgangskoden er ikke ændret.
• Subordinate clause: ..., at adgangskoden ikke er ændret.

So after at, Danish does not use the same main-clause word order rules.

You will see both styles.

In Danish, a comma before a subordinate clause like at adgangskoden er ændret depends on comma style. Many writers include it, and many learners find it helpful because it makes the sentence easier to read.

So both of these can be seen:

• Det ser ud til, at adgangskoden er ændret.
• Det ser ud til at adgangskoden er ændret.

The version with the comma is very common and very clear.

Yes. A few natural alternatives are:

• Det lader til, at adgangskoden er ændret.
• Det virker, som om adgangskoden er ændret.
• Det ser ud som om adgangskoden er ændret.

These all mean something close to It seems / It looks like the password has been changed.

Small nuance differences:

• det lader til = rather neutral, often like it seems
• det ser ud som om = very close to it looks as if
• det virker, som om = it seems as if / it appears that

Your original sentence is perfectly natural.

Yes, that is a helpful way to think about it.

ændret is the past participle of ændre = to change, but in a sentence like adgangskoden er ændret, it behaves very much like an adjective describing the state of the password.

Similar examples:

• Døren er lukket. = The door is closed.
• Vinduet er åbent. = The window is open.
• Adgangskoden er ændret. = The password is changed / has been changed.

So it comes from a verb, but in this structure it describes a resulting state.