You can change the browser that System Manager uses from the tools menu in the upper left corner. Select Tools, then Options. In the "Browser Path" option, I put "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" to use Chrome. If you want to use Firefox or Safari, then enter the path for that browser. Once changed, close the browser and restart System Manager (re-open it using the short cut or Start Menu).
If nothing comes up in Edge so that you can't even edit the options to change the browser used, then there is a bit of a workaround...open System Manager and let Edge start (and fail to display anything). Copy the link, something like "http://127.0.0.1:50378?sid=xxxxxxx", and paste it into a different browser. If it has an error about System Manager being open already then close Edge and refresh the page. Then change the browser it uses.
Hope that helps.
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