boyfriend has trust issues

So my boyfriend seriously thinks I purposely try to snoop and sneak to see what's he doing on his phone as he picks it up and I just so happen to look his way but it directly to his phone my intentions are never to care what his doing on his phone because I don't care I trust him enough to not have to feel like I have to snoop but he assumes that I do it gets me angry and upset inside because I'm truly not like that and it sucks because he never believes me so it's like soon enough it's going to make me depressed I feel like it's never going to end this cycle with him not trusting me. He also turns around on me when I'm on phone as if I'm trying hide what I'm doing on my phone I don't care if he looks I have nothing to fucking hide he swears as soon as he looks towards my direction I try going back on my phone so he can't see what I'm doing but the truth is I'm probably on IG for the 8th billion scrolling down  seeing the same stories posted. I don't know what to do,to make him believe me that I really don't fucking care what he looks at I'm not trying to be those annoying ass gf by he is truly making up one for no reasom and it cause a lot of arguments. It's like he like to argue for no reason he tried to pick a fight I swear I'm not doing anything out of the ordinary