Maybe try a style with longer legs. I've found that the "trunk" style boxer briefs (short inseam) usually fit me like briefs instead of the picture, and generally don't fit that well. I find the long ones to have too much fabric (annoyingly too much fabric) but maybe those are for you. I tend to like the medium length boxer briefs, or just true briefs with no legs at all.
You gotta get the right size man. They come in 4 different sizes. You sure you're buying the right size?