How cooker oven Thermostats work & how to replace

This along video sorry please skip to your appropriate time for your type of cooker
Watch time list
Convection oven 2.25 min
Fan oven 4.40 min
Fan oven with separate grill thermostat 10.30 min
Digital electronic oven with pcb and ntc sensors 12.40 min
How to replace a thermostat 15.50 min
How a thermostat works 25.10
Beer donation information 29.25 min