1- I think you might receive a better answer if you ask (about your problem with the transitions timing on the text added to the photos) in the Premiere Elements forum.
2- Since I can't give you a direct answer- I am suggesting a workaround which would require that you redo most of the work of creating this slide show.
Instead of adding text during the slide show creation process, you would make a copy of the photo file for each photo that you are using in this slideshow -- then for each photo use the TEXT Tool of the Photoshop Elements Editor to add the words to each of the copy photo files. Then make the slide show again using the "copy photo file with the text on the photo" for each image where you use added text.
I know my workaround is a significant amount of work. I definitely recommend experimenting with only a few photos to verify that you can get your desired result. You need to take these tests to whatever will be the media format of your slideshow playback.
If the ultimate destination ofr this slideshow video will be a DVD disc, I recommend using a read/write DVD while you are testing and then using a DVD-R for the final result.
It should be possible to select the text thumbnail in the PRE media browser, then right click and choose overlay or separate slide. In the sceneline click the transition icon before or after the text.