Geeetech A10 glass bed

[GaryM]

Hi guys I'm very new to 3d printing and I'm ready to pull my hair out!

I bought the superplate glass bed for my a10 which is obviously thicker than the plastic bed that came with the printer. I have the bed the lowest it can go but it's still not enough room for the hot end nozzle as it touches the base.

How do I manually set a new height for the z axis please? I've gone into the settings and adjusted the home height but it doesn't save the adjustment it goes back to default. Please help!