Are you using resource leveling?
See Resource tab, leveling options.
There you will see a drop down box which enables you to select the leveling "resolution".
As Rod says, try it first at week-by-week, then maybe day-by-day if necessary.
Turn off all of the other checkboxes and see if there is an acceptable solution without them.
Click level all.
Leveling delays tasks to remove resource over-allocation.
You can see how much each task got delayed by inserting the leveling delay field as a column in the entry table.
If you are not using the resource leveling functionality, and you are trying to "even up" everyone's work manually, then it will become increasingly difficult and perhaps impossible.
Best to let the software do the work.