Hi Eleni,
I have a similar question. There seems to have been an update in the past two weeks or so that has changed functionality of several things (the Teams app also has some issues).
I am in New Outlook, I have Outlook open in a browser tab on my second monitor. I used to have calendar reminders pop up on my main monitor, on top of all my windows, and stay there until I dismissed it. Now, both Alert and Browser Notifications settings say they disappear automatically and there is no option for the alert to show on top of other windows (screenshot below).
Without this, the existing calendar notifications are basically useless because I am working in other windows, other browser tabs, and with a million other sound alerts going off, it's too easy to miss a simple ding.
The support articles posted in the response don't show these updates.
How can we access the other options to have alerts on top of all windows and remain until dismissed?
Thanks!