Office 365 (Web) - Change Outlook Light to Outlook on the Web
Outlook compatibility is typically best with the current or immediately previous version of Internet Explorer or Firefox, and the latest version of Chrome or Safari. To check to see if your browser is up-to-date, go to https://updatemybrowser.org/. If you are opening Outlook on an outdated browser, it will switch to "Outlook Light" which has limited features. After you update your browser, you may need to turn off the "Outlook Light" settings.
1. Click on the Settings icon in the upper right and select Options.
2. Click on General and select Outlook Web App Version.
3. Uncheck the box next to "Use the light version of Outlook Web App" and click Save. You will need to sign out and sign back in for the updates to take effect. To sign out, click on the avatar or your picture in the upper right and select Sign Out.