Help Phone doesnt go back to 4G

[Double Del]

Hi everyone, my Im in a non 4g area the phone switches to 3g, but Im back in a 4g area the phone doesnt go back to 4g unless i power down then turn it back on. Any ideas on how to force phone back into searching for 4g. Im in los angeles.

 

[ironhorse]

Airplane mode then out will force to search for a new signal.