I changed from 2x24" monitors to 1x24" and 1x32" monitor, the taskbar is on the 24" but anything I maximize on that monitor doesn't take into account the taskbar, so everything is cut off on the 24".
This is on Manjaro KDE.

I've tried switching the primary monitor and messing with some other settings, but I'm not able to fix this.

What am I missing?

Thanks.

Upon reboot, all is fine. But, after the machine locks and it sleeps, the 24" monitor can't maximize windows properly. =(

Okay, if 24" is set to primary, it maximizes properly after Sleeping.
Power Management -> Energy Saving -> Screen Energy Saving

The 24" *FORGETS* it is the primary monitor after rebooting, neither monitor is primary after rebooting, yet the TASKBAR is still on the 24", but the checkbox
Display and Monitor -> Display Configuration -> Primary
forgets it's checked state.

Okay, upon further digging, I found files in
/home/me/.local/share/kscreen
that reflected both monitors.

*BOTH* files had the lines
"primary": true,

So I flipped, needed sudo, the 32" to false. Now it is fixed.

*BUT* the values are NOT matched by what is displayed under

Display and Monitor -> Display Configuration
Neither has primary checked after rebooting.

Also, another file had

"primary": primary,

neither
"primary": true,
nor
"primary": primary,

causes the Checkbox for primary monitor on
Hardware -> Display and Monitor -> Display Configuration -> Device
to be checked.

There is certainly a bug here, or the file in question in
/home/me/.local/share/kscreen
Doesn't control the primary monitor