Problem with Geeetech A30: Z Axis is 2-3mm above the bed at the start of the print

[makerbiles6]

I got my very first 3D printer and wanted to test it by printing the benchy. So I added the printer in cura via custom fff printer, entered the dimensions, filament size, heated bed etc. After putting in filament and leveling the bed I started the print and the printer started, but the nozzle wasn't nearly where I leveled it, but rather 2-3 mm above the plate. Obviously i canceled the print.

Did anyone have the same problem or know where this may come from? Could false settings in cura be the cause or did I fail at leveling the bed correctly? Or is it something I totally missed?

I researched on the internet and I saw you can set an z offset value in your starting gcode. Should I just try to find a value to lower the nozzle?

Thanks for your help!