Hello L644,
Good morning! Thank you for posting to the Microsoft community. We will be happy to help you.
Based on your description I advise you to uninstall your Outlook and install it back and check if the issue persists.
To uninstall new Outlook:
- From the Startmenu, select new Outlook for Windows.
- Select the arrow to expand the list option in Start.
- Select Uninstallto begin the uninstall process.
To reinstall new Outlook:
- Open classic Outlook for Windows.
- In the top corner, you'll see a toggle to Try the new Outlook
.
- Select this toggle to download the new app and you will switch to the new Outlook for Windows.
If the issue persists and the user cannot still see the toggle to revert to classic Outlook. Kindly follow the steps in the attached document Toggle out of the new Outlook for Windows preview - Microsoft Support
If you toggled into the new Outlook for Windows preview from classic Outlook for Windows, every time you try to launch classic Outlook for Windows you'll be redirected to the new Outlook for Windows preview. You can go back to classic Outlook for Windows by selecting the toggle in the new Outlook for Windows app.
**Note:**You may not see the toggle if classic Outlook for Windows isn't installed on your device. For help installing classic Outlook, follow the instructions in You can't open classic Outlook on a new Windows PC.
If for some reason you don’t see a toggle in the new Outlook for Windows, try these troubleshooting steps:
- Make sure you try to launch classic Outlook for Windows from the Windows Start Menu, not the new Outlook for Windows. The new Outlook for Windows has a “New” tag on its app icon. For classic Outlook, select the icon without a “New” tag.
- From the Windows Start Menu, type “Registry Editor” in the search box and select the Registry Editor app.
- Navigate to the following path: Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
- Scroll to the bottom of the list to and double click on UseNewOutlook.
- Enter 0 in the Value Data field.
- Attempt to launch classic Outlook for Windows from the Windows Start Menu.
**Tip:**Remember to choose the app icon that doesn't have a Newtag.
We look forward to hearing from you! Thank you for your valuable time. Have a nice day!
Sincerely,Simbarashe | Community moderator