rjuarezp I think Plasma has a lot more configuration options...
That's undoubtedly true, but even Plasma doesn't have a setting that allows turning this feature off. It's just a standard feature - it's simply the way the scroll wheel works when the mouse is pointing at the speaker volume control. Perhaps if I used the same mouse you use, holding its "DPI button" down might have the same effect here.
And this is not only true of Plasma. I just tested Budgie, GNOME, Xfce, Plasma, and MATE. With all of those Solus DEs, if you put the mouse pointer on the "speaker" icon in the system tray, and spin the mouse wheel, the volume changes, and there's a visual indication of the % from muted to 100%.
Apparently your mouse has a way to switch that feature on and off, and it's currently turned on.
EDIT: Please realize that I'm not doubting what you said happened. I'm sure it's happened exactly as you described it, both here and on the Mint forum. I'm just pointing out that your solution probably applys only to users who have the same model of mouse you use, while others don't need a special mouse to get this normal behavior.
