Drops of urine on underwear

I am male. I have a problem that when I pass urine and I have finished and wash my hands then majority of the time a small amount of urine will come out onto my underwear. This happens irrespective of me sitting for awhile longer so that all urine can come out. What I currently do is that I wash than wipe with toilet paper and then wash again, is this permissable and what is muftis advise to me in regard to this. Do I have to change my underwear everytime I pass urine.