I use the Colemak layout on Windows 10 version 1803 (April 2018). I’m aware that I can switch back to a Qwerty layout by hitting Windows + Space, but occasionally my layout would switch anyway and I knew I wasn’t hitting this shortcut. It turns out that there’s another keyboard shortcut that does the same thing - either Alt+Left Shift or Ctrl+Left Shift. In my case, it was the latter. Here’s how to fix this.

First, open settings. Choose Time & Language and then Region and Language. Next, click Advanced Keyboard Settings below “Related Settings.” Then click “Languag bar options” below “Switching input methods.” This opens a dialog box, choose the “Advanced Key Settings” tab. You should see something like this:

Click “Change Key Sequence” and then choose “Not assigned” for both “Switch Keyboard Layout” and “Switch Input Language.”

Hit “Ok.”

Now you should be less prone to accidentally change your layout in the middle of trying to get things done!