How to change default cell formats in Excel 2011?
For existing (or the one you get from others) Excel documents where you have a lots of data in it, try using the down arrow (under the format window).

It will open new window where you can choose a new format there. 

Next right click on the cells you want to modify, or just create new cells.

Another way for existing documents you get from others do following:
Open and than click on the "Import Cell styles" than select your format file (both files have to be open at same time).

For new documents use your saved template.

PS. One day you will succeed giving your template to your coworkers and teaching them to use it, so you do not have to reformat theirs.

Here is my screen capture showing the original and SAMPLE after modifying.
Hope this helped, and you can impress your boss with your excel skills.