Which certificates are trustful?

I noticed alot of weirds certificates that are trusted by default both my android phone and google chrome , ones like chinese gov or japan gov then i asked myself why i should trust an foreign gorv? What's certificates i need if i only use google don't have facebook and mostly use the internet with cookies disabled ? And what happens if i visit a page that uses an certificate i no longer trust? And how can a certificate can pose an risk to myself or my identify or data ? And how remove them would make me more safer (By trustful i mean that won't spy on me or infect me with malware)