Time Machine Restore, permissions problem
I just concluded a clean install of of Yosemite 10.1 to my iMac (21.5", late 2009 model, 3.06GHz Intel Core 2 Duo, 12GB DDR3, 500GB--nearly that much available now), using Time Machine for a full backup before the install. I did not create an image of my hard drive as well. Using Time Machine in an attempt to restore files from several folders I have discovered I do not have permission to view my own folders. Looking through older backups on the T.M. HDD I see my current user name doesn't match the pre-install user name--it's now capitalized where before it was all lower case. I am assuming this to be the problem.
I'm the administrator on this machine. I looked through System Preferences > Users & Groups but only saw how to change a password. I also looked in the SysPrefs > Security & Privacy but didn't find anything useful there. I attempted to create a new user with the "correct" user ID (all lower case) but was prevented because "another already exists", presumably the capitalized user ID.
Q: Is it easier/better to (a) change my user name to match what it has always been--my preference--or (b) change the permissions of the folders I wish to restore from?
Q2: How do I do either?
I cannot restore anything necessary on my iMac.
Suggestions, please.
iMac, OS X Yosemite (10.10)