Making the "Fun" key a lock, rather than a shift
The default Atreus layout requires you to hold down the "Fun" key while typing keys on the "Fun" layer. You can change that behavior to work more like Caps Lock.
First, you need to install Chrysalis, our configuration GUI. You can find instructions for that at https://keyboard.io/atreus.
Once you've loaded up Chrysalis with your Keyboardio Atreus plugged in, click on the Fun key
Click on “Caps Lock” to assign it to the key.
Click to open the "Layers and keymaps" section of the sidebar
Change the setting from "Shift to Layer" to "Lock to Layer"
Click the Save button in the bottom right hand corner.
Now the "Fun" key will toggle the Fun layer on and off instead of requiring you to hold it down to access the Fun layer.