Outlook 365 desktop app launching Internet Explorer / Default Apps cannot be changed from IE

I have two places where Office apps persist in launching IE 11-

- when adding  a gmail account - the google security prompt is launched in the IE11 context which of course google no longer accepts.

- when clicking on the "Get Signature templates" link in the e-mail signature dialog

This is a new build Windows 10 with Office 365 apps from a Microsoft 365 E5 subscription account. 

I also cannot change the default app for some file extensions, only IE or Store are availalble : .xsl .website .partial

also in the protocols URL:RES

Of course there is an Office365 account associated which has been used on other older systems before Edge was invented. 

The gmail is expecially annoying, can anyone help?