I have a standard ender 3 w/4.2.7 motherboard
When I go to Control/temp and set nozzle temp, bed temp and fan speed then try to save it I get a beep but after turning off the printer my presets are lost.
What am I doing wrong?
Those are defined by g-code. The menus are used to override these values while printing or to set a temperature for working on the printer.
You cannot turn on the printer and have a specific temperature preset. Same goes for fan speed.
The only thing you can set is the values used for pre-heating materials.