In the Mouse & Keyboard pane, you can view and configure the mouse- and keyboard-related settings.
To open these settings, choose Actions > Configure > Hardware, then click Mouse & Keyboard.
Mouse
If you play games in a virtual machine, the Mouse menu allows you to set how to use a mouse:
Auto-detect for games. This is a recommended default setting. If you're working with a guest OS application, the mouse moves freely between the guest operating system and macOS. However, when you start a game, the mouse input is automatically captured in the virtual machine so that you couldn't move the mouse to macOS by mistake and automatically released when you quit the game.
Optimize for games. If your mouse accidentally moves to macOS when you're playing a game, select this option to make the mouse work in the virtual machine only. To release the mouse input and switch to macOS, press Ctrl + Alt.
Don't optimize for games. In some rare cases, Parallels Desktop may detect an application as a game and the mouse starts working incorrectly with the application. If you have this problem, choose Don't optimize for games.
Mouse pointer sticks at window edges
When working with a virtual machine in Window view mode, you may often need to move the mouse pointer to the edges of the virtual machine window to display various guest OS items: for example, to display the Start menu in Windows 8, hidden taskbar in Windows XP, or macOS menu bar when any of the guest macOS applications is running in full screen.
The Mouse pointer sticks at window edges option makes the mouse pointer pause for a while at the edges of the virtual machine window and you won't move the mouse outside of the virtual machine window by mistake. To move past the edge, just move the mouse quickly.
Keyboard
Choose Optimize for games from the Keyboard menu if you actively use the modifier keys Option (Alt), Ctrl, and Shift in action games. When this option is selected, signals from these keys are processed immediately.
Linux virtual machines on both Intel and Apple Silicon Macs have been known to have occasional issues with scrolling sensitivity, where a mouse pointer may start to behave erratically when using a trackpad for scrolling. If you encounter such a problem, you may adjust the scrolling sensitivity to your liking by executing the following command in macOS Terminal:
$ defaults write "com.parallels.Parallels Desktop" "HID Host Hook.Scroll Sensitivity" X
where X is the inverse scrolling sensitivity value. The default one is 20, and the maximum is 120. Make note that 120 means the lowest possible sensitivity. With the value set to 120, you would need to work the trackpad very energetically to scroll in the Linux VM.
Note: This command only works in Parallels Desktop for Mac 19.3 or newer and affects the scrolling sensitivity only in virtual machines, not your main macOS system.