Have changed all washers and reseated taps in shower but shower head still leaks

SOURCE: WATER DELIVERED FROM SHOWER HEAD NOT HOT ENOUGH

I think some shower valves have a safety setting to prevent burning. maybe you could adjust that to be hotter.

SOURCE: leaking shower head

Check the spout pull knob . Debris can be keeping it from closing completely.

SOURCE: The shower hose leaks from the connection between shower hose and

have you tried teflon tape? wrap it around about 7 times and you will be fine.

SOURCE: leaking faucet

Most likely bad solder joint or leak where shower arm is screwed into fitting.

SOURCE: The shower head is leaking. I disassembled the

You need to pull and replace the cartridge on your shower valve most likely. It varies by Make and Model, but generally, remove the handle, remove any sleeve around the center spine, remove the round trim plate, close the service stops, remove the retaining clip or ring, and pull the cartridge straight out of the valve body by pulling on the spline... or get a cartridge puller. Then take your cartridge to the store and get a new one. Flush the valve body by slightly opening both service stops and then install the new cartridge and reverse the process.
Generally this problem occurs when sediment has torn part of the sealing o ring on the cartridge. If you send me the make/model and/or a picture I will give you the specific instructions