The thumb buttons are usually the first to "stop working". Most of the time they're not broken at all. They've just been told to do something else.
First, Test Them
Open the mouse button test and press both side buttons. If they light up, the hardware is fine and the problem is the app you're using. If they don't, keep reading.
The 7 Fixes
- Reset the mapping in your mouse software to Back and Forward (buttons 4 and 5).
- Check onboard profiles. Some mice store binds on the mouse itself.
- Update your browser. Very old browsers can't see buttons 4 and 5.
- Close other mouse apps. Two utilities can fight over the buttons.
- Reinstall the driver in Device Manager, then restart.
- Try another USB port and computer.
- Check the game's settings. Some games need you to bind Mouse 4 and Mouse 5 manually.
When It's Really Broken
If the buttons don't light up on two different computers with the software reset, the switch is dead. Side-button switches are cheap but fiddly to replace.
Why Side Buttons Are Different
The left, right and middle buttons are handled the same way by every operating system. Side buttons are a little different. Browsers and most apps treat them as Back and Forward, but games, design apps and mouse software can map them to anything. That flexibility is great, but it also means side buttons are the easiest to accidentally break with a setting. A profile you set up for one game, a macro you forgot about or a second mouse app can all take them over.
Step-by-Step: Finding the Cause
- Open the mouse button test and press each side button. Note whether it lights up.
- If it lights up, the hardware works. The problem is in the app you're using, so check that app's keybinds.
- If it doesn't light up, open your mouse software and look at what the buttons are mapped to. Reset to the default profile.
- Check for onboard memory profiles. Some mice store mappings in the mouse itself, which persist even if you uninstall the software.
- Close other mouse or keyboard utilities (macro tools, accessibility tools, remappers) and test again.
- Try the mouse on another computer.
By the end of these steps, you'll know whether it's settings, software conflict or hardware.
Side Buttons in Games
Many games don't bind side buttons by default. Open the game's control settings, click the action you want, and press the side button. It should show as Mouse 4 or Mouse 5. If the game shows a keyboard key instead, your mouse software has remapped the button to that key. That can be fine, but it can also clash with other binds. For the cleanest setup, leave the side buttons as Mouse 4 and Mouse 5 in your mouse software and bind them inside the game.
Side Buttons on Mac
macOS doesn't use Back and Forward buttons as widely as Windows. Safari and Chrome usually respond to them, but Finder and many apps ignore them unless you install the mouse maker's software or a small utility that maps them to shortcuts. If they light up in the button test but do nothing in Finder, that's why. It's a software limitation, not a fault.
When the Hardware Is to Blame
Side button switches are small and get pressed at an angle, so they wear differently from main buttons. A side button that needs a hard press, works only sometimes, or feels mushy may have a worn switch or a cracked plastic actuator. Switches can be replaced, though side switches are smaller and fiddlier than main ones. Check your warranty first.
Check What the Buttons Send
Side buttons normally send "Back" (button 4) and "Forward" (button 5). Press each one on the mouse tester. If they light up, the hardware is fine, and the problem is the app or game you're using. Many games need you to bind the buttons in their own settings before they do anything.
| Result on the tester | What it means |
|---|---|
| Both buttons light up | Hardware OK, check app or game bindings |
| Neither lights up | Software has remapped them, or a driver issue |
| One lights up | That button's switch may be faulty |
| Lights up only sometimes | Worn switch or loose contact |
Fixes to Try
- Open your mouse software and reset the buttons to their defaults.
- Check whether a profile or game mode has changed the buttons.
- Close macro tools like AutoHotkey and test again.
- Unplug the mouse, restart, and plug it back in.
- On a Mac, install the brand's software or a tool that adds back/forward support, because macOS ignores them in some apps.
Side Buttons Pressed by Accident?
If you keep pressing them by mistake, you can disable them in your mouse software, or try a mouse with buttons placed further back.
Quick Summary
- Check the buttons online first to rule out hardware.
- Games often need you to bind side buttons in their settings.
- Reset buttons to default in your mouse software.
- Close macro tools that may intercept the buttons.
- On a Mac, extra software may be needed for back and forward.
- If only one button fails, its switch is the likely cause.
Remapping Side Buttons the Right Way
Want your side buttons to do something useful? Use your mouse software to map them, but keep one profile with the defaults (Back and Forward) for everyday use. Many people map side buttons to copy and paste, push-to-talk, or switching virtual desktops. In games, bind them in the game's settings instead, so they show up as Mouse 4 and Mouse 5. That way you avoid conflicts between the mouse software and the game, and your binds still work if the software isn't running. If something stops working after a change, reset to the default profile and test again with the button test.
Summary
Test the side buttons first. If they light up, fix the app or game binds. If they don't, reset your mouse software, close other utilities and try another computer before deciding the switch has failed.
Frequently Asked Questions
Why do my side buttons type letters?
They've been remapped to keystrokes in your mouse software.
Do side buttons work on Mac?
Yes, in most browsers and apps, but some Mac apps ignore them.
What are mouse buttons 4 and 5?
Back (4) and Forward (5), the two thumb buttons.