How do I adjust speed, I want to decreese the speed a bit.
Is it: Motion/ACCEL : 1000 ( can I simly change to 800, do I have to adjust any other variables as well, or will extruder head motor automatically adjust to reduce speed if ACCEL is decresed)
Acceleration is acceleration, not speed.
To adjust speed during a print the easiest way is to rotate the control wheel without going into the menu.
In the third line on the left, you can read the Feedrate in %. That’s what you are looking for.
Another way would be going into menu --> tune --> speed while printing.