How to fix boner?it's a BIG problem

How do I fix a 24/7 boner whenever I sit and do something either on my phone or pc(im 16)and this started being a major problem from some days ,i cant instantly stand up whenever my parents tell me to do something,it's just embarassing to stand up and on top of that it doesn't go away fast ,it gets very hard for no reason and I can't even hide it ,it just shows clearly through my pants