When you first boot up NeoLemmix you will see a drop-down menu of three different hotkey layouts, which are (I think) Functional, Traditional and Minimalist. I believe it's useful to copy this over to the Configure Hotkeys menu. Because if the player accidently chooses the wrong option there's no easy way to get this back, and instead must go through the tedium of changing one control at a time. Thanks.
Good idea. Will look at implementing this for the next update (it very likely can be backported to V12.7.X without much effort, so if another minor update happens, I'll see if I can include this in it).
Implemented in commit 8c59c75. If a V12.7.4 update happens, I'll see how feasible this is to backport (I think it should be relatively easy to do); otherwise you'll get this feature in V12.8.0.
Workaround for now: If you want to change to Traditional layout, just delete the "hotkeys.ini" file in Settings. If you wanted one of the other layouts, rename your Settings folder to something else, then run NL and choose the desired setup when prompted (NL will think this is the "first run"). Then, exit NL and copy all files from the old settings folder except hotkeys.ini, into the new one.
Alternatively, if you want minimal layout, you could simply blank out (but not delete) "hotkeys.ini", which would give you a completely empty hotkey setup. Then, manually configure the 5 assignments the minimal layout has (if you even want those) - scroll wheel up = zoom in, scroll wheel down = zoom out, MMB = pause, RMB = click-to-scroll, Esc = quit.