Daily Conversation

Is it okay to say “No problem” instead of “You’re welcome”?

Hi everyone, when someone thanks me, I often say “No problem.” But I heard that some people think it's not very polite. Is it okay to use it in daily conversation?

Is it rude to say “What?” when you didn’t hear someone?

Hi everyone, When I don’t hear someone clearly, I sometimes just say “What?”. But someone told me it might sound rude. Is that true? What do native speakers usually say instead?

Is it okay to say “How is it going?” instead of “How are you?”

I’ve heard native speakers say “How’s it going?” a lot. Is it the same as “How are you?”