How to Set the Default Account in Outlook
To set the default email account to the account you prefer to use:
Go to the File tab. Select Info. Select Account Settings > Account Settings. Highlight the account you want to be the default. Select Set as Default. Select Close.
Set the Default Account in Outlook for Mac
To set the default account in Outlook 2016 for Mac or Microsoft 365 on a Mac:
Go to the Tools tab and select Accounts. Select the account you want to make the default account. The current default account appears at the top of the list. In the lower-left corner, select Settings (gear icon) and choose Set as Default.
To send a message from an account other than the default account, select the account under Inbox. Any email you send will be from that account. When you are finished, select the default account under Inbox again.
