Repaired an italian job machine and now fully working

How do i change the stake down from 25p to perhaps 10p, ive found the DIL switches but dont seem to make an effect.
Also, how do i clear the memory on the board? i read it was by pressing the function button on the mpu and the red hopper switch, which takes me to the menu on the display... and then hitting cancel for 5 seconds - this does nothing
And one more for now

How much do i need to fill the hopper to get it full or at least able to pay out?
i dont have a refill key - do i need one?
thanks in advance!
ade