In the search field type: default browser and hit Enter. Or just click Choose a default browser from the top of the search results.
That brings you to Settings > System > Default apps and the Web browser option is already highlighted. Edge is set as the default.
To change it click on Microsoft Edge and a menu of browsers you have installed on your PC pops up. Choose the one you want, and close out of the screen.
Edge is no longer the default browser, it will be the one you selected.