Mouse wheel jump forward/back works in windowed mode only, not in full screen

In Options / Keys, I set Jump FWD/BWD to Mouse Wheel Up/Dwn, which works great in windowed mode, but in full screen mode the mouse wheel controls volume. Am I missing a setting somewhere? Thanks!

MPC-HC (64-bit)
---------------

Build information:
   Version:            1.9.24 (ffe50c0c7)
   Compiler:           MSVC v19.29.30145
   Build date:         Nov 12 2022

LAV Filters:
   LAV Splitter:       0.77.0.1
   LAV Video:          0.77.0.1
   LAV Audio:          0.77.0.1
   FFmpeg compiler:    MinGW-w64 GCC 12.2.0

Operating system:
   Name:               Windows 11
   Version:            10.0.22621 (64-bit)

Hardware:
   CPU:                11th Gen Intel(R) Core(TM) i7-11390H @ 3.40GHz
   GPU1:               Intel(R) Iris(R) Xe Graphics (driver version: 30.0.101.1338)
   GPU2:               Intel(R) Iris(R) Xe Graphics (driver version: 30.0.101.1338)

The mouse key options are listed twice. Once for windowed and once for fullscreen.

In case you did not know, there is already a default keybinding for Ctrl+Mousewheel to do seeking.

sorry, didn't see it, had to scroll to the right. Feel dumb now. Thanks!