Mine switches to MICROSOFT EDGE when it needs to view a PDF file... Then when I am done I close out Windows EDGE and go back back to Google Chrome or FIREFOX browsers...
I don't normally use the EDGE but use GOOGLE CHROME and FIREFOX... I only use EDGE here to view PDF files text and to play the game 'World of Solitare' hehe...
These two has never auto-changed to EDGE as default.
EDGE does a whole couple of pages of settings from the three ... labeled more when you move the mouse to it. This is on the upper task bar right hand area.
My EDGE has DEFAULT SEARCH set for GOOGLE SEARCH. There is a large list to select from...
Roy Ken