Timeslips does not control this, your Outlook account settings do.  Timeslips just 'hands off' to your default Outlook account.  Have your IT person change the default account in Outlook for you.

Thanks.  If only there was such a thing as an IT person at this small firm.

And it's odd.  I set up my Timeslips just a few months ago without an IT person; Sage assisted me to get things up and running.

Correct, but again, all we did was tell Outlook that we would be handing off some emailing duties.  The whole "which account does it send from" is controlled by Outlook, not Timeslips.