Changing to a different lens on a fiber laser

I have a Monport GP30W fiber laser. I want to use a different lens. I want to switch from a 150 x 150 mm to a 70mm x 70 mm. I use a MacBook. How do yo change the setting to us the 70mm? I know I go to device settings and also maybe duplicate devices. after that I am lost.

We have a guide on changing lenses on a fiber laser here:

the above includes the duplication you already mentioned. The next step is focus.

Note: Some manufacturers give you the calibration information for your new lens, and we strongly recommend you check their website before proceeding to perform the calibration manually.