Your electric heater will have a temp control:
Often times it is on the back or side of the heater (note it may be embedded under a cover) that cover could be made of plastic or cardboard. Some I have seen are covered with some tape holding the cardboard or plastic. Usually they are a about 1.5" wide by about 3" long and the thermostat is a block that has the wires connected on the front side along with the dial to change temp setting (most settings are factory set around 125-130 'F) I would not suggest going much if any higher than that. The back side is has the temp bulb on it and it must be in contact with the wall of the tank - if you are experencing cooler water temps and it is set at 125, then check your t-stat operation, you likely have a faulty t-stat or element.
If you water is too hot and it is set at 125 then your sensor may be loose and not making good contact with the side of tank - therefore it keeps trying to get the sensor up to 125 but cant if not making good contact.
On another note one of my previous campers had a remote temp sensor - the block that the wires are attached to was actually screwed to the wall of the trailer (under the countertop where the heater was located) but the sensor was on a wire to a well in the tank. But this would be a rare type of heater, may have been added from and after market kit - yours is most likely intregrated on the terminal block and stuck to the side of tank.
Once you uncover the controler:
it should look something like this:
They are usually on the back side so you will have to go in a counter top pulling out drawers to addess or under a closet etc. It should be located may be under a plastic cover kinda like this:
And yes your gas control also had a themperature control also (othwise it would just stay on if it never know when to cycle gas off)
it may or may not be adjustible I have seen both.
But most likely it is something like this:
(note this one is adjustible - see metal lever to slide side to side)
Depending on brand Sometimes adjustible - sometimes not like this Attwood which has a fixed non-adjustible temp control:
Hope this helps.