I haven't been able to do anything regarding my tree for the past week because I want to be sure I have enough time to fix it completely in one sitting. But I want to thank Barbara for her helpful hints. I want to be sure that I don't lose current or backup files by not doing the process, and renaming current files, properly. Because I am convinced that my online file is the most correct and up-to-date, I will rename my FTMMac file [and media folder if it doesn't do it for me]. Will all the media links be revised to show the new name? And then I will download and link the "current" online file without renaming. Hopefully that will prevent any mishaps with that file, authorized people, etc.
And ivykeep, just for your added info, I did compact my file several times and rebooted my system. I am convinced that ancestry.com had sync problems that I was unlucky enough to get into the middle of. The reason I want to keep my online tree and not attempt to sync now [hopefully the problems are solved] is that if I begin to sync, I get a message box saying there are conflicts in information for lots of people and it then shows lots of FTM changes that need to be uploaded to ancestry.com. There should be zero, or at least very few that originated in FTM. I cancelled the sync at that point. BTW: Can you force a sync in one direction only? Probably not, as that is essentially what I will be doing by the above.
Wish me luck in the next few days.