Welcome Christina Goodridge,
Thanks for reaching out to Microsoft Q&A Forum. I understand that emails in your Outlook.com inbox only open when you double-click them, which opens a new window. You would like a single click to open the email on its own, without the message list and other columns showing alongside it.
To narrow down the issue, could you please confirm:
- Are you using Outlook.com in a web browser, or the new Outlook for Windows app? If it's a browser, which one (for example, Edge or Chrome)?
- When you single-click an email now, does nothing happen at all, or does the email get selected without opening?
Please make sure you already tried the Q&A Assist steps. In addition, please try the following:
1, Hide the reading pane so emails open in full view
- Select the gear icon in the top-right corner to open Settings
- Go to Mail, then Layout
- Under Reading pane, select Hide reading pane
- Select Save, then refresh the page
- A single click should now open the email across the full page. Use the back arrow to return to the inbox
2, Collapse the folder pane to reduce the number of columns
- Select the three-line menu icon at the top left, next to Home, to hide the folder list
- The folder pane will stay collapsed until you select the icon again
3, Make sure messages do not open in a new window by default
- In Settings, go to Mail, then Compose and reply
- Clear any option that opens messages or replies in a new window, then select Save
4, Test in a private browser window
- Open an InPrivate window (Edge) or an Incognito window (Chrome) and sign in at outlook.com
- If single-click works there, the issue is likely caused by browser data or an extension
5, Try a different browser
- Sign in to Outlook.com in another browser to see if emails open with a single click
Looking forward to your update.