IPhone 8 not receiving text alerts?

When I'm on and using my phone, it doesn't give me alerts when I receive a text. I need help immediately because I can't respond to texts when I want to

Is this a good idea?

He wants me to buy two iPhones for him because he's not 18 yet he's 17. It's for some people he know, he sell iPhones to people. Should I do this?

How do I get rid of old Apple ID data?

When I was younger I used my mums Apple ID on my iPhone. I bought music etc. Now I'm older I have my own Apple ID but every time I set up a new phone I'm asked for my mums Apple ID password because some of the data on the phone comes from that… I can't do that for the rest of my life! How do I prevent this connection between our accounts? Would I have to delete the data?