Why is APN setting not visible?

Please try and help me with an answer that is not too tech talk. I bought a galaxy s7 a month ago. The phones carrier was sprint but i have at&t. Before you say im not able to use this, i was and i am. Up until yesterday i have had an entire month using att on this phone. i reset my phone because of adware. The phone keeps trying to finalize update each time phone has been turned on. Could this be an issue for the apn settings not showing? I really need to reach that ApN so i can actually put in my settings to have service.

You will need for the phone to boot before you can do this. You say the phone is trying to finalize. Presumably this doesn't happen so what does? It certainly won't be because of APN settings
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I dont think you understood what i am getting at. The phone HAS booted. It has been on. I have restarted phone, gone to different places for Wifi for it to finish and it always says successful, but continues to happen each time i reboot phone. This happened once when i got the phone and i was told the APN settings were not visible because it will not complete the update correctly. I know the Apn is not causing it to finalize. I NEED it to finalize so i am able to PUNCH IN my apn settings. apn is not visible like it has been up until this point.

You may wish to read this Cannot change apn setting on sprint | Samsung Galaxy S7 Edge

Not much help, thanks anyway