Tub/shower fixture has very little hot water, every where else in hse is fine, this is a two handle fixture... I don't know the name as of right now, do these twin handle fixtures have an adjustment anywhere??

Usually no adjustment necessary especially if it used o run fine. Likely some dberis got into the valve. Do you know if this is a stem , cartridge or ball valve, its clogged.

do these twin handle fixtures have an adjustment anywhere???
No! Most work on a stem, washer and seat assembly, (see image)
Shut the water off and renove the stem and washer assembly. Noew turn the water back on to flush out any trash that may be lodged in there.; You should have a strong stream coming out of the open valve body. If not take a wire and poke it past the seat and trey to break up anything that's in there. If still no joy then click on back and tell us about it. Good luck, Tom

You may also have loose washer that prevents hot water from full flow... Do as Tom said.