galaxy iphone samsung 7+ s8 glitches

possibly a already analyzed topic but with a new twist. i've bought a new mavic pro. i'm 52, retired, and humbly intelligent. my old iphone 5 is messing up. i WAS going to get an iphone 7 plus and a mini 4 for my drone. however, my local drone shop guys (way younger than me) all say to...