Learn Hardcore Indonesian: Saya lupa kata sandi akun itu. - I forgot the password for that account.

itu means "that." In Indonesian, demonstratives come after the noun, so akun itu = "that account." Without itu, akun is generic/unspecified. For "this account," use akun ini.

Can I put "itu" before the noun, like "itu akun"?

Not when it modifies a noun. itu goes after the noun: akun itu. Before the noun, itu functions as a pronoun: Itu akun saya = "That is my account."

Is kata sandi akun itu the same as kata sandi dari akun itu?

Yes—both mean "the password of that account." The bare noun–noun pattern (kata sandi akun itu) is the default and concise. kata sandi dari akun itu adds "of/from" and is also common, especially for clarity. Very formal: kata sandi milik akun itu (stiff).

Do I need a preposition after lupa (like akan/pada/dengan/sama)?

No. lupa can directly take a noun: Saya lupa kata sandi akun itu. lupa akan/pada is grammatical but formal/literary. Colloquial lupa sama/dengan occurs, but is unnecessary.

How do I say "I forgot to..." instead of "I forgot the..."?

Use lupa + verb:

Saya lupa mengunci pintu. (I forgot to lock the door.)
Saya lupa memasukkan kata sandi. (I forgot to enter the password.) Formal style can add untuk: Saya lupa untuk mengunci pintu.

Is saya necessary? Can I use aku or drop the subject?

saya = polite/neutral: Saya lupa...
aku = informal/intimate: Aku lupa...
Jakarta slang: Gue/gua lupa... You can drop the subject when clear from context: Lupa kata sandi akun itu.

How do I show "I've (already) forgotten it"?

Add sudah: Saya sudah lupa kata sandi akun itu. This emphasizes the current state of not remembering. For recency, add time words like barusan (just now) or tadi (earlier).

What's the difference between kata sandi, sandi, and password?

All can mean "password."

kata sandi: standard/official; common in formal UI.
sandi: also common, especially in apps/UI (e.g., Masukkan sandi).
password: widespread in everyday tech talk. Mixing is normal: Saya lupa password akun itu. Avoid sandi kata; it doesn't mean "password."

Is kata sandi written as two words? What about katasandi or a hyphen?

Standard writing is two words: kata sandi. katasandi or kata-sandi is nonstandard, though you may see katasandi in code or UI labels.

Does akun always mean "account"? How is it different from rekening?

akun = account in digital contexts (email, social media, app logins). rekening = bank account. Say akun Instagram, akun Google, but rekening bank (not akun bank).

Can I replace akun itu with a possessive like "my account"?

Yes. Examples:

Saya lupa kata sandi akun saya. (my account’s password)
Saya lupa kata sandi akun Anda/kamu. (your account’s password)

What does the suffix -nya do here?

-nya marks definiteness or "its/his/her."

Saya lupa kata sandinya. = "I forgot the password" (or "its password," if the referent is clear). You can also say kata sandi akunnya = "the password of his/her/its account" (context decides whose).

Can I front or emphasize parts of the sentence?

Yes:

Yang saya lupa adalah kata sandi akun itu. (What I forgot is that account’s password.)
Kata sandi akun itu yang saya lupa. (colloquial emphasis) Neutral base order remains Saya lupa kata sandi akun itu.

How do I pronounce the sentence naturally?

Stress typically falls on the second-to-last syllable:

Sa-ya (SA-ya)
lu-pa (LU-pa)
ka-ta (KA-ta)
san-di (SAN-di)
a-kun (A-kun)
i-tu (EE-tu) Say it smoothly: SA-ya LU-pa KA-ta SAN-di A-kun EE-tu.

How do I make it plural, like "those accounts' passwords"?

Indonesian often leaves number to context. To mark plural explicitly:

kata sandi akun-akun itu = those accounts’ passwords.
Formal reference to a previously mentioned account: akun tersebut; plural: akun-akun tersebut.

How could I say this politely to support staff?

Saya lupa kata sandi akun itu. Bisakah Anda membantu saya meresetnya/mengatur ulangnya?
Maaf, saya lupa kata sandi akun tersebut. Mohon bantuannya untuk reset.