Live graphic driver problem

[measter]

I haven't been able to solve this on my own. I've tried 3 different pclos .iso/s w/ the same problem; I'm trying to boot a live off Ventoy USB. The splash screen resolution is ok, but when I get to the desktop, whether it is KDE or Mate, my resolution is 800x600 and I can't fix it in the live.

I often use inxi to help me understand driver problems.  Here is the difference between a satisfactory LM Cinnamon live boot and an unsatisfactory pclos live boot:

LM Cinn:
$ inxi -G
Graphics:
  Device-1: AMD RS880 [Radeon HD 4200] driver: radeon v: kernel
  Display: x11 server: X.Org v: 1.21.1.3 driver: X: loaded: ati,radeon
    unloaded: fbdev,modesetting,vesa gpu: radeon resolution: 1366x768~60Hz
  OpenGL: renderer: AMD RS880 (DRM 2.50.0 / 5.15.0-56-generic LLVM 13.0.1)
    v: 3.3 Mesa 22.0.5

PCLOS KDE Darkstar 2023.01.30
$ inxi -G
Graphics:
 Device-1: AMD RS880 [Radeon HD 4200] driver: N/A
 Display: server: X.org v: 1.21.1.6 driver: N/A note: try sudo/root
   resolution: 800x600~75Hz
 API: OpenGL v: 4.5 Mesa 22.3.4 renderer: llvmpipe (LLVM 14.0.6 128
   bits)

I see the note about try sudo/root but I don't know what to 'try'.

[measter]

I forgot to mention some strategies I've tried:
adding the monitor res to the boot parameter in the form of vga=788 (as I recall)
adding nomodeset to the boot parameter
no joy

[measter]

I forgot to mention some strategies I've tried:
adding the monitor res to the boot parameter in the form of vga=788 (as I recall)
adding nomodeset to the boot parameter
no joy

Doh!

Somehow I posted this to the wrong forum; I intended to post it to the PCLOS forum.  My bad.