Kossel Pro leveling issues

Hey guys, I need your expertise. I have a Anycubic Kossel Pro and I am trying to set it up and having the darnest time. The Z-axis is not set up and ramming down hard on the bed.

So I downloaded Pronterface and attempted to follow the instructions of this anycubic video:

[www.youtube.com]

But the printer still reads my home as z=270 and z= 0 goes down to a couple inches above the bed. When using Pronterface I can manually step down the nozzle to the bed which turns out to be z= -18.2 but if I attempt to make that my new z=0, like with code g92 z0 code, that command will not stay with the machine or have memory of it. If I turn off the machine, it has no memory of the new settings. So while this video is informative, I'm not figuring out how to actually change it's settings of what true 0,0,0 is. The video refers to adjusting the tightness of the belts, but how does that change the setting?
Any would be wonderful!

You could add the whole Z-leveling procedure to the startcode of your slicer. Then you wouldn't have to send it on every restart and the firmware stays unchanged.

I take it that this is a delta printer that homes to Z max@270, you should have a setting to set Z length that you need to adjust so that Z0 is the nozzle just touching the bed.(normally in eeprom if enabled)