Dear Melanie Leon1,
Good day! Thank you for posting to Microsoft Community. We are glad to assist!
According to your description about "Change the default browser for opening links in Outlook" To understand the situation and be able to offer you relevant suggestions, we would need a little more information from you. Kindly help us in providing the following information.
- May I know your current environment? Is It Exchange Hybrid, on-premises exchange (Exchange server) or pure cloud?
- May I please confirm that you get same situation when default browser is selected under Link handling? To check this kindly open your Outlook go to File-->Options-->Advanced-->Scroll to Link handling then choose Default browser-->Ok then close outlook and re-Open it to check if it will make any difference.
If you don't have this feature kindly refer to Open file links directly in Office desktop apps - Microsoft Support
- Would you mind to kindly provide the screenshot of the outlook version are you using? Kindly go to File-->Office Account
This requested information will help us to narrow down the scenario and find the right troubleshooting.
We are looking forward to your response! Thanks for your precious time. Have a nice day!
Sincerely,
Inema | Microsoft Community Moderator