I just bought an inexpensive 3d printer, AdimLab. I have been 3D printing for years, but only with printers that must be connected to a PC (no display for control and no SD slot). This one has a display an SD slot and lots of settings so it can run standalone and print from the SD card. I can’t figure out how to set the Z height with the built-in controls.

What I have done so far (The printer is not connected to the PC or any software yet):

After homing each axis, I set both sides of the X axis carriage to the same height from the base frame. Then I leveled the bed surface manually using a piece of paper to ensure the nozzle is the same height off the bed in each location around the bed.

Results:
Now, when I try to print, the nozzle is too high and the filament is not sticking to the hair sprayed bed. My question is, how do I adjust the Z height down a couple tenths of a mm after the bed is leveled?

I would google to find out how to do the bed leveling. I would assume there is some routine for it.
that would be the place to start.

There also appears to be a facebook group for the printer so search there also. Usually it is a good resource.