It's probably the only program I despise, but need. I want to use small button under the wheel as middle click (I have short fingers), and until now, the only way to do it is/was to use logi options+. LO+ updater will get stuck on update every couple of months and while it's updating my button configuration doesn't work. Solution? kill process, uninstall, reinstall and hope it will not get stuck again any time soon.

I have to test Mauser.

While I am here, can anyone recommend good alternative mouse with both smooth/quick and precision scroll like logitech's? Back and forth buttons are also a must for me, horizontal scroll optional. Ideally a mouse would save configuration onto itself, so I don't have rely on garbage software like LO+.

Reassign the button - maybe possible with Karabiner

The scroll isn't anything special but you might find something that works for you (there's a large lineup), corsair make an ok mouse that can save multiple hardware profiles, and is programmable with input remapping and macros, etc.