2008 Keeway Super Shadow

no...Full is on...res is reserve...Pri is Prime.
Do not leave it on prime !!! This is for re-filling the carbs when they have been emptied.
It is a vacuum operated tap, when switched to full or reserve, fuel only flows when the engine turns over...prime flows fuel all of the time.
The tap should be set to full unless fuel is running low.
Leaving it on prime when not running can lead to serious engine damage !!!

The float valve in the carb is sticking or the float height setting is incorrect or the float has a hole in it.
Do not use Pri on your fuel tap until this is sorted as it could cause hydraulic lock in your engine, which will wreck it. Fuel will flow through your carb into the engine when it is parked.
This will also ruin your engine oil as the fuel will mix with it. Check the oil level to see if it has increased...

I also have a keeway super light 125 and the tire pressure is 33 PSI in the front and back.

Run 36psi front and rear

add oil

I cannot locate the sparkplug for my scooter, I have a Keeway F Act-50....

most likely a short in the wiring, but a good idea is to fist confirm that the battery is being drained, disconnect the negative battery cable and connect the black lead of a amp meter to the negative terminal of the battery and the red lead to the negative battery cable, now, with the key in the off position the amp meter should read 0, if not your going to have to have lots of patience finding that short, but try to work in a systematic and organized way... wish u luck