Ao mudar as definições de privacidade, eu limito quem pode ver as minhas histórias.

Ao mudar is a very common European Portuguese structure. Literally it’s:

• ao = upon / on / when (doing something)
• mudar = to change (infinitive)

So ao mudar as definições de privacidade is roughly:

• "By changing / When I change the privacy settings"

Grammatically, ao + infinitive works like an English "when/while/by + -ing":

• Ao abrir a aplicação, vejo uma notificação.
  When I open the app, I see a notification.

In English we use a gerund (opening), but in Portuguese, especially in European Portuguese, this ao + infinitive construction often replaces the gerund.

In Portuguese, after ao in this structure you must use the infinitive form of the verb, not a conjugated form.

• Correct: ao mudar, ao comer, ao sair
• Incorrect: ao mudo, ao como, ao saio

Think of ao + infinitive as a fixed pattern, similar to English “on doing / upon doing”, where doing is not conjugated for person. The subject (I, you, we) is understood from context or expressed elsewhere:

• Ao mudar as definições de privacidade, eu limito…
  When I change the privacy settings, I limit…

Very close, and often interchangeable:

• Ao mudar as definições de privacidade, eu limito…
• Quando mudo as definições de privacidade, eu limito…

Both can mean “When I change the privacy settings, I limit…”.

Nuances:

• Quando mudo is a straightforward time clause (when I change).
• Ao mudar can feel a bit more like “by changing / in changing”, sometimes with a slight focus on the action as a means to an effect.

In everyday speech, in this kind of sentence, they’re effectively equivalent.

You can absolutely drop eu:

• Ao mudar as definições de privacidade, limito quem pode ver as minhas histórias.

In Portuguese, subject pronouns (eu, tu, ele, etc.) are often omitted because the verb ending already shows who the subject is:

• limito = I limit
• limitas = you (singular, informal) limit
• limita = he/she/you (formal) limits

Adding eu can:

• add emphasis: Eu limito (I myself limit, not someone else)
• clarify in longer or more complex contexts
• sound a bit more formal or explicit

So both versions are grammatically correct.

In definições de privacidade, de works like the English “of” in a compound noun:

• definições de privacidade = privacy settings / settings of privacy

Here, privacidade behaves more like a category or type, not a specific, previously mentioned thing. In that case, Portuguese normally uses de + noun (without article):

• configurações de segurança – security settings
• política de privacidade – privacy policy
• nível de brilho – brightness level

Da privacidade (= of the privacy) would point to some specific, already-identified “privacy”, which is not the idea here. We’re talking about privacy in general.

Both can be used in tech contexts, and you will see both.

• definições (plural of definição)

  • Very common in European Portuguese UI (menus, phones, apps).
  • Often translates English “settings”.

• configurações (plural of configuração)

  • Also common, especially for more technical or system-level settings.
  • Can suggest configuration or a more technical setup.

In many everyday app contexts, definições de privacidade and configurações de privacidade would be understood the same way. On a Portuguese phone, the “Settings” app is typically Definições.

In European Portuguese, the normal pattern with possessives is:

article + possessive + noun

So:

• as minhas histórias – my stories
• o meu telefone – my phone
• a tua conta – your account

Dropping the article (minhas histórias) is possible, but in European Portuguese it often sounds:

• more emphatic or stylistic, or
• more poetic/literary.

In everyday speech from Portugal, as minhas histórias is the standard, natural choice. In Brazilian Portuguese, minhas histórias (without the article) is much more common and neutral.

The possessive agrees in gender and number with the thing possessed, not with the owner.

• minha / minhas – with feminine nouns
• meu / meus – with masculine nouns

Examples:

• a minha história / as minhas histórias – my story / my stories (história is feminine)
• o meu vídeo / os meus vídeos – my video / my videos (vídeo is masculine)
• a minha conta – my account
• o meu perfil – my profile

Both are possible, but they’re not identical:

• quem pode ver as minhas histórias

  • Focuses on permission / access.
  • “who is allowed / able to see my stories”

• quem vê as minhas histórias

  • Focuses on who actually sees them (in practice).

In a privacy-settings context, the idea is about who has permission or who is allowed, so quem pode ver is the more natural choice.

Quem is used for people (or groups of people) when you mean “who”:

• quem pode ver as minhas histórias – who can see my stories

Que is normally “that/which” (for things, or as a general relative pronoun), and qual/quais is “which”. In this sentence:

• que pode ver as minhas histórias would sound wrong, because que doesn’t by itself mean “who” here.
• You could say as pessoas que podem ver as minhas histórias (the people who can see my stories), but then que refers back to as pessoas, not directly to “who”.

Since we’re directly talking about who can see the stories (people), quem is the right pronoun.

The Portuguese presente do indicativo is flexible. Eu limito can mean:

1. Habitual / general action

   • Whenever I change the settings, I limit who can see my stories.
   • This is the most natural reading here.

2. Immediate present (less likely in this exact sentence, but possible in others)

   • Right now, I am limiting…

In this context:

• Ao mudar…, eu limito… is best understood as a general rule or habit.
• English would often use either simple present (I limit) or present progressive depending on context, but Portuguese uses the simple present for both kinds of meanings more freely.