Invert Scrolling for an External Mouse on Mac

Plug a normal mouse into a Mac and the wheel often feels inverted, because macOS applies natural scrolling to it just as it does to the trackpad. Flipping it is easy. Flipping it for the mouse only is where people run into a wall, so here is the honest picture.

Inverting it

1. Open System Settings.
2. Click Mouse.
3. Turn off Natural scrolling.

Your mouse wheel now moves the page the way it does on Windows.

Why your trackpad changed too

macOS does not store a per-device scroll direction. There is a single system-wide preference, com.apple.swipescrolldirection, and both the Mouse and Trackpad panes are editing the same value. Turning it off for the mouse turns it off everywhere.

This catches out a lot of laptop users, who want the trackpad to keep behaving like an iPad while the mouse behaves like a mouse. macOS has never supported that, and no hidden preference unlocks it.

What are your options?

• Pick one direction and use it everywhere. Simplest, and most people settle within a couple of weeks.
• Use a third-party input driver. Utilities exist that intercept scroll events and can treat devices differently. That is the only way to genuinely split them, and it means running an extra background process that has access to your input.
• Use your mouse's own software. Some higher-end mice from Logitech and others can invert the wheel in their own driver, which sidesteps the macOS setting entirely.

To be clear, Mainspring flips the same system-wide setting macOS exposes. It applies instantly rather than needing a logout, but it cannot separate mouse from trackpad either, because that setting simply does not exist in macOS.

While you have the mouse in hand

Scroll speed is a separate setting worth tuning, and if a Magic Mouse has stopped scrolling entirely, that is usually something else.

Every setting here is a one-click, reversible toggle in Mainspring — no Terminal, and an undo button on all of it.