How to keep natural scrolling on the trackpad but not the mouse on a Mac

macOS has one Natural scrolling switch for every trackpad and mouse, so they always scroll the same way. To give each its own direction you need a small app. Bothways is a free one: it keeps natural scrolling on the trackpad and gives a wheel mouse the classic direction.

Why the trackpad and the mouse share a direction

Natural scrolling moves the page the way your fingers move, as on an iPhone. That feels right on a trackpad. On a wheel mouse most people expect the older way, where rolling the wheel toward you takes you further down the page.

macOS shows the switch in two places: System Settings, Trackpad, Scroll & Zoom, and System Settings, Mouse. Both are the same setting. Turn it off for the mouse and the trackpad changes too.

What macOS offers

Only that one switch. You can pick the direction that suits one device and get used to the other, or flip the switch each time you plug the mouse in.

Fix it with Bothways

Out of the box Bothways gives the trackpad and a Magic Mouse natural scrolling and a wheel mouse the classic direction. It works with the macOS switch on or off, so you can leave it alone.

Download Bothways, open the disk image and drag Bothways to Applications. If you open it from anywhere else, it offers to move itself there.
Open Bothways. Its icon appears in the menu bar and its Settings window opens.
Click Open Accessibility Settings and switch Bothways on. macOS asks for this before any app may change how scrolling works.
Scroll. The trackpad follows your fingers and the mouse wheel scrolls the classic way.

To change a choice, click the menu bar icon to open Settings, then set Trackpad, Magic Mouse or Mouse to Natural or Standard. Sideways scrolling follows the same choice decides whether scrolling left and right flips too.

Two mice, two directions

If you use two different mice, say one at your desk and one in your bag, find the one you want to change under Each device in Settings and give it a direction of its own. Bothways knows that model again each time it connects. Two mice of the same model share one choice. If your version of macOS doesn't say which device sent a scroll, Settings tells you, and each kind of device keeps its one choice.

If it doesn't work

The menu bar arrows have a dot at their lower right. Bothways is still waiting for Accessibility. Switch it on in System Settings, Privacy & Security, Accessibility. If it is on already, click Reset and try again in Bothways' Settings. In Terminal, tccutil reset Accessibility ai.lfglabs.bothways does the same, and then you switch it on again.
The mouse still scrolls the wrong way. Another scroll app may be running. Two apps changing the same scroll can undo each other, so Bothways warns you when it finds one and offers to quit it.
You want the Mac's own direction for a moment. Right-click the menu bar icon and choose Pause. Choose Resume to turn Bothways back on.