Shower head drips while filling tub

I was reading a previous post and I have the same problem. Filling the tub and water comes from the shower head. Wife hates it. We used pex from the valve to both outlets with drop ear 90s. The tub spout was not set right so we used copper pipe with sweat on male adapters to get the right length, brass nipples were either too long or short. Walls are all sealed up and I'm not sure what to do to fix this, i need to make the wife happy