External monitor with 16" MBP?

[Matt2012]

I just got my new 16" M1 Max today and being a bit of Mac newbie still, I can't figure out the resolutions between the laptop screen and my external monitor?
I want to use my 38" external monitor as the main monitor (3840x1600) which I've set up as the main display but looking at the laptop, its using the same resolution as the external monitor so looks bad.

How do I use the external monitor as the main monitor and use the laptop as abn extended display using the MBP's native resolution?

If i click on the MBP in display setings, I just the mirror option only?

 

[nollic]

If you open up the Display Settings (apple menu, System Preferences, Display, Display settings) a pop up should appear where you can choose mirrored or extend display.

The pop up can in some instances hide behind other windows and/or display on only one of the screens IIRC.