I have the very same problem as ZIncKatz, and I am grateful to learn that Outlook doesn't have a volume controller. It's not me who couldn't find a way to adjust the volume, it's a feature of the programme that the sounds are barely audible!
It is very reassuring that "support engineers" are around to offer help on how to adjust the volume on a system-wide basis.
And that the "support engineers" refer to the menu bar as "the Apple bar".
And recommend (for no reason whatsoever) to close all applications first. (Whatever it may mean to "close" an application. On my Mac, I quit applications, but I close windows, and that is not the same thing at all: most applications are still running even when their last windows are closed. It's not a Windows operating system!)
I wonder whether that "support engineer" has ever done more on a Mac than clicking on the speaker icon on the "Apple bar".