In most years, a new folder is created for the templates and this folder also contains the attributes for the "look and feel". The easiest way to revert back to your older settings is to use the Reports -> Show Templates Folder menu item. This will take you to the "OfficePool Files 2011" folder.
If you back up one directory level (Application Support folder) you will see a "OfficePool Files" folder. In this folder you will want to copy "BracketStyles.css" and "MasterStyles.css" files and place them in the "OfficePool Files 2011" folder.
Keep in mind that there were some changes in 2011 so you may lose these changes when reverting back to older files.
Another option is to open these files up in a text editor and manually transfer the needed styles.
A final option is to make these changes from within OfficePool using the Reports -> Modify Report Syles... and Modify Bracket Styles... menu items.