In ACT! ver. 6 when working w/activities under the "Activities" tab, you used to be able to click into the individual field (Date, Time, etc.) and change just that particular field.
Since that excellent version vanished, to do any kind of edit to existing activities requires opening up the whole event screen. Inefficient, if you ask me, just to change 1 item like the time, don't you agree?
Hopefully someone else will agree & put forth a change in the next version?