Att APN issues with Straight Talk

[SAWYER]

I have an ATT GS3 and it will allow me to add a new apn but after while it will delete the new apn and go back to the att apn. I tried apn backup and restore but it will not work on Android 4.0+ devices

 

[ImDonly1]

I added the ST APN to my S4 and it stays. It won't let me delete the ATT APN, but you just pick the ST one and it stays. Not sure why your phone deletes it?

Maybe try free a ATT bloat free ROM? Or I bet if you root, you could delete the APN?