What's the difference between the settings? Is it that Global Mode scans radio frequencies (including the LTE/CDMA frequencies and GSM frequencies) until it finds a compatable frequency? So maybe in the US it would avoid additional scanning time by setting it to LTE/CDMA? Or is it more complicated than that?
This is a really good question. Frankly, I find that toggling between the two can resolve certain connection issues, but typically it doesn't matter. In the US, (and on VZW) you're connecting to CDMA. I'd leave it on global mode if you like, being in the US you won't incur roaming charges because it's all domestic regardless, but LTE/CDMA should work just as well.