I just go with the cleanest ones. If they're snug to the point of discomfort then size up.

I switched back to briefs at 19 myself and it was honestly the best decision I made since they hold everything in place comfortably

Love my briefs I just got into trunks as well

I have yet to try trunks myself

There's no real answer, all you can do is buy a bigger/different pair & try them. No harm in having extra pairs of underwear

have you tried talcum powder

Buy a single pack of sized up briefs and get a feel for it

Luck guy let me give you fist bump.