Learn Hardcore French: Choisis un mot de passe simple, puis change ce mot de passe souvent. - Choose a simple password, then change that password often.

It’s the imperative mood, used for commands and instructions. In French imperatives, the subject pronoun (tu, nous, vous) is omitted: you say Choisis ! (not Tu choisis !) and Change ! (not Tu changes !). Here both verbs address a single person with the informal tu form.

Why does Choisis end in -is while change has no -s?

They follow different imperative patterns:

For regular -ER verbs like changer, the tu imperative drops the final -s: Parle !, Change ! (not Parles !, Changes !).
For -IR verbs of the “second group” like choisir, the tu imperative ends in -is: Finis !, Choisis !.
Exception to the -ER rule: before the pronouns y and en, you add back -s for euphony: Parles-en !, Vas-y !, Changes-en souvent !. But with other pronouns, you don’t add -s: Change-le souvent !

Can I say this politely or to more than one person?

Yes, use vous: Choisissez un mot de passe simple, puis changez ce mot de passe souvent.

Is there a neutral/instructional alternative to the imperative?

Yes:

Infinitive instruction style: Choisir un mot de passe simple, puis le changer souvent.
Polite request: Veuillez choisir un mot de passe simple, puis le changer souvent.

Why repeat mot de passe? Can I use a pronoun instead?

You can (and in French it’s very natural):

Affirmative imperative: pronoun after the verb with hyphens: … puis change-le souvent.
Negative imperative: pronoun before the verb: … puis ne le change pas souvent. If you phrase it with changer de mot de passe, the pronoun is en: … puis changes-en souvent.

What’s the difference between changer le mot de passe and changer de mot de passe?

Changer le mot de passe treats it as something you modify; it’s common in tech/UX wording: Changez votre mot de passe.
Changer de mot de passe emphasizes replacing it with a different one: Changez souvent de mot de passe. Pronouns reflect this:
le with direct object: Changez-le souvent.
en with changer de: Changez-en souvent.

Is mot de passe masculine or feminine, and how do I make it plural?

It’s masculine: un mot de passe. The plural is des mots de passe (only the first noun takes the plural): not mots de passes.

Why is it de and not du in mot de passe?

Because de here introduces a noun complement that specifies type or function, not possession or a specific instance. It means “password” as a compound noun, not “word of the pass/the past.” So it’s mot de passe, not mot du passe.

Why passe and not passé?

Passe is a noun here (related to “a pass/permit” in older usage). Passé with an accent means “past” (adjective/noun) or a past participle. Mot de passé would be incorrect.

Where should I put souvent? Is the position at the end okay?

Yes. With simple tenses:

Typical: after the verb: Change souvent ce mot de passe.
Also fine (slightly more colloquial or emphatic on the object): Change ce mot de passe souvent.
With a pronoun: Change-le souvent. All are acceptable; choose the one that sounds most natural in your context.

What’s the nuance between puis, ensuite, and après?

puis and ensuite both mean “then/next”; ensuite may feel a touch more neutral in speech, puis is very common in writing.
après is often used as a preposition (après ça, après cela, après cela, change…) or as après, … in informal sequencing. In your sentence, puis or ensuite are the cleanest choices.

Does the position of simple change the meaning?

Yes.

un mot de passe simple = a simple/easy-to-remember password (literal descriptive meaning).
un simple mot de passe = merely a password, nothing more (restrictive/evaluative meaning). Your sentence needs un mot de passe simple.

Why ce mot de passe and not cet mot de passe?

Use ce before masculine nouns starting with a consonant: ce mot. Use cet before vowel sounds or silent h: cet ordinateur, cet homme, cet hôtel.

Should it be un mot de passe or ton/votre mot de passe?

Both are possible:

un mot de passe when you’re telling someone to create one (indefinite, a new item).
ton/votre mot de passe when referring to the person’s specific password: Choisissez un mot de passe simple, puis changez-le souvent. or … puis changez votre mot de passe souvent.

How do I pronounce the tricky parts?

Approximate guide (IPA in slashes):

Choisis: “shwah-zee” /ʃwa.zi/
un: nasal “uh(n)” /œ̃/
mot: “mo” /mo/
de: weak “duh” /də/
passe: “pass” /pas/
simple: “san-pl(uh)” /sɛ̃pl/
puis: “pwee” /pɥi/
change: “shahnzh” /ʃɑ̃ʒ/
ce: “suh” /sə/
souvent: “soo-vahn” /su.vɑ̃/

Is the comma before puis necessary?

It’s optional and stylistic. A comma before puis is common to mark a brief pause: …, puis …. You can also write it without the comma in a short sentence: Choisis…, puis change… or Choisis… puis change… both read fine.