I am traveling to the UK in a couple of months and wish to use a local providers SIM for the duration of my trip. I am aware that my S7 Edge is globally unlocked from the factory. What I need is to know how to fix the APN settings on this phone. They are greyed out in the menus and not accessible. From EVERYTHING I've read, you MUST change APN settings when using another networks SIM to get data and MMS to work. How do I ungrey the APN settings on the Verizon Galaxy S7 Edge?