Outlook default email

PeterCWorth 

You can try creating new outlook profile and set your primary email address as default. Basically, whatever email address you set up first will be the default one.

For Windows: https://support.microsoft.com/en-us/office/create-an-outlook-profile-f544c1ba-3352-4b3b-be0b-8d42a540459d#:~:text=In%20Outlook%2C%20select%20File%20%3E%20Account,profile%2C%20and%20then%20choose%20OK. 

For Mac: https://support.microsoft.com/en-us/office/manage-profiles-or-identities-in-outlook-for-mac-fed2a955-74df-4a24-bef6-78a426958c4c#:~:text=Add%2C%20change%2C%20or%20delete%20a%20profile&text=Ctrl%2Bclick%20or%20right%2Dclick,then%20launch%20Outlook%20Profile%20Manager.&text=%2C%20and%20then%20enter%20a%20name%20for%20the%20new%20profile.&text=Double%2Dclick%20the%20profile%2C%20and,new%20name%20for%20the%20profile.