I find that if I click on the timeline or another object, the title edit is completed and seems to "take". I doubt that it should make a difference, but I use PE9 on a 64-bit Windows 7 machine.
I have never experienced, nor have I heard of a Title edit not taking. Just to make sure that you are working in the proper Panel, when you have created a Title, you would Dbl-click on that Title, either in the Timeline, or in the Project Panel. This will open it in a little sub-program, Titler, where the Title was likely created. One can tell that they ARE in the Titler, by the unique Toolbar there. The artist's palette is easy to spot. Once that Title is open in the Titler, there are Selection Tools, that can be used to Select elements for modification, and also the Text and "drawing" Tools. If one has existing Text in the Title, it can be edited with either the Direct Selection Tool (the "arrow"), to move the Text block around, or with the Text Tool (the "T"), to edit characters. Those changes should be immediately applied, as soon as one clicks away from the Titler. Unless one does a Save for the Title as a Template, all changes and saves are done in the XML instructions in the PREL (Project) file. The Title does not exist as a discrete file.
Now, I am not using PrE 9, so cannot comment on there being a Bug in the Titler and its operations, but so far, no one has commented on having issues with modifications to Titles not sticking.
Also, remember that what one has on the Timeline is an Instance of that Title in the Project Panel. If the Title has been used several times - several Instances of it, and one then edits the Title, those changes will be global and will affect all Instances of that Title.
Good luck, and let us know more about your workflow, in case this IS a Bug,
I would recommend, for best results, that you click on the Done button in the lower right of the Titles panel when you want to leave the Titler and return
to the Edit workspace.
Thanks. I had omitted the Done button - duh!