To change the default browser in Outlook 365, go to File > Options > Advanced, then scroll to “Link Handling” and set “Open hyperlinks from Outlook in” to your preferred browser, like Chrome.

As announced, Microsoft has integrated a function into its new Outlook to open the PST files of the classic version. Firstly, you must be subscribed to Microsoft 365 and have also connected the ...

Some users reported that every time they open the classic Outlook app on their computer systems, the Outlook (new) app opens in place of it automatically. Maybe you had made the switch by mistake..