This is actually very easy.
On the right side you should see the design explorer. It is the list of features in the drawing. If you do not see the list then turn it on by going to the menu View>design explorer.
Now you should see a set of features. These features are in order they are created. The Features list also has a + or a - beside it that would hide or show what is in the list. Down the feature list you will see hole1, hole2, hole3, etc. If you right click a feature in the cad drawing you will get an option to Show Feature in explorer. Right click the hole you wish to edit and select Show in explorer.
The sketch under one of the holes will highlight. Right click that sketch in the explorer list and select edit.
You will get a sketch with the center point of the hole/holes. The holes will not be shown just the points. Use your dimension tool under the sketch icons to dimension from the datum to the hole center. Change the dimension to what you would like it to be in both direction.