Please follow the instruction from below simple video (suitable for all A1 model)
If you want to change Y axis Home position, please go to main function, enter F5 parameter setting and then input password 520.
So, you can go in to change parameter. Using MPG to change home position. If you want to run F1 Y axis home offset (controller will ask you whether confirm homeset).
Please check above video for the Y axis home position setting process.Attach are some manual pages for reference.