How do I get my net10 iphone 7 plus to send mms/ picture messages?

I bought a used iphone 7 plus today on net10 prepaid service. It works fine to make calls, send text, and use the net. It will not send mmspicture messages though. I heard it is something about the APN but can't figure out how to fix it.

If I go under settings, then general, then profile, it says configuration profile: reseller. If I click on that, it says

Signed by: not signed
Description: reseller

Contains: Cellular settings

Then under that you can click "More details". When I click that, it comes up Cellular settings, and has an option for "Advanced settings". When I click that, it comes up "APN Name: reseller".

Can anyone help me? I really need to be able to send pic messages.

How do I permanently block all numbers not in my contacts?

I have an iPhone 8, and it seems really shady that the only way to block calls is to manually do each number. Seems like they want you to buy some sort of service. I don't like the do not disturb function because I like being notified of texts and apps. I would like to automatically block ALL numbers not in my contacts. They just change numbers if they want to spam me. Is there a free app, or some overlooked setting I can switch on?

Just got new iPhone XR, I hate it?

I got the iPhone XR about 2 months ago because it was time for an upgrade. When i first received it i had issues with camera quality and The app snapchat. I tried to get used to it but i can't. I need a new phone what is the best option?

Would it be crazy to go back to a basic phone?

I feel like smartphones have ruined us. I've disconnected from social media and can no longer access my accounts, however I feel like it still isn't enough. I'm still addicted to my iPhone.
Would it be nuts for somebody in their early 20's to ditch smartphones and go back to a basic one with standard features like text and call?