I'm having a problem with my hot water in my master bathroom shower.

All Other showers and fausets have no problem.
The master shower, seems to only give us luke warm water. The fauset is a single lever type which should mix the hot and cold to our liking. But what is happening when you try to mix the hot and cold , even if you turn the fauset to hot you only get luke warm water.

What to do ?

Fred

Your mixing valve is partially blocked, possibly by some lime/scale that came from your hot water heater. Shut off your water, remove the handle, remove the valve stem and clean the valve. Sometimes it is a good idea to soak the stem in 1:3 parts of vinegar water or CLR.

I'm having a problem with my hot water in my master bathroom shower.

All Other showers and fausets have no problem.
The master shower, seems to only give us luke warm water. the fauset is a single lever type which should mix the hot and cold to our liking. But what is happening when you try to mix the hot and cold , even if you turn the fauset to hot you only get luke warm water.

what to do ?

Fred
It could be (assuming it's a newer pressure balanced valve) that the balancing spools have gone points up.

Replacing the balancing spools is fairly straightforward, but only if we know the brand and model of the valve in question.