Q: iPhone 5s requires reset network settings after turning off/on

I have a problem I can't find elsewhere in the forums. I just received an iPhone 5s (Verizon-compatible, using Straight Talk service, iOS 9.1). Whenever I turn the phone off/on, I have no service or 0 bars. If I choose "reset network settings," I have a network connection when the phone reboots. But the same happens if I turn phone off/on again.

Once I fix that problem, I'm still trying to enable my data settings, which I've so far had no luck with, despite following all Straight Talk instructions. Following their instruction always requires me to turn off/on, so every time I try, I then have to reset network settings to get access again.

Thank you for your help!

Teddy