First, let’s go through the entirely legitimate process. To change the “From” address, you need to make the “From” field visible. Open a new email in Microsoft Outlook and then click Options > From. This will make the “From” field visible.

The "Options" tab showing the "From" button.

To change the “From” address, click the “From” button and select one of the email addresses you’ve added to Outlook.

The "From" button.

The email address in the “From” field will change, and when you send an email, it will be sent from that address.

The "From" field showing a different email address.

If all you want to do is quickly switch between your email accounts when you’re sending emails, that’s all there is to it.

Send an email from an account that you haven’t added to Outlook

Compose a new email and then click on the “From” button again. From there, select the “Other Email Address” option.

The "Other Email Address" option.

In the panel that opens, type in the address you want to send an email from and click “OK.”

The "Send From Other Email Address" panel.