When I open the app it shows it saying "Verizon" but then I just a blank white screen and it doesn't load
Have you uninstalled the app and reinstalled to see if that cleans it up? You might need to remove data/cache as well when/before uninstalling.
Yea, and I don't know how to clear cache on an iPhone app. I tried this (how to Clear application cache on iPad - Apple Community) but it didn't work
It has these steps
1) Open an app, preferably one thats likely to store lots of cache data.
2) Hold the power button until the power off slider appears.
3) Then hold the home button until the application quits to the home screen.
4) Notice the iPad/iPhone will hang for a few seconds.
5) Now your idevice has been updated to lightning fast iOS again. - Works well with a hard reset also.