We’ve had issues where scrolling the mouse wheel causes the active window to zoom / the font size to change even though ALT isn’t held. The fix:
Tools > Options > Keymap >
Search for “zoom”
For “Zoom Text In” and “Zoom Text Out” select Clear (instead of the default “Alt+MOUSE_WHEEL_UP”/DOWN).
Now select edit and set the key combination to: CTRL + SHIFT + Up/Down