Try holding down the Ctrl key (the Cmd key on a Mac) as you add slides to your timeline. This will override the ripple feature so the music won't move as you add new stills.
You don't say which version of the program you're using, but this feature varies just a bit from version to version.
For now -- in order to undo what you've done -- I'd recommend removing the clips that have had the audio knocked out of alignment and re-adding them to your movie. Re-aligning audio and video can be just a bit tricky.
I watched the adobe movie titled "arranging clips in a movie" and it said to hold down the Alt key which I did but didn't notice that it changed all the sound on my videos - it didn't affect my soundtrack. Then I saved and shut down the show - therefore next time I opened it I noticed what had happened to it and it was too late to undo.
That is what I am doing now (deleting every clip and re-adding them) just thought there might be a better way as we are meeting our friends who went on our holiday with us this weekend and this will take me forever.
I'm using Premiere Elements 13.
One of the ways to unlink audio from its video in a video clip is to hold down the Alt key and click and drag the audio portion away from the video portion. When you do, you get the "offset number" that you are seeing on the video and audio portion after the unlinking. Did you really want to unlink the audio from video for that clip? If not, do not use the Alt key as you did. Now that you have separated you audio video with the Alt way, have you tried holding down the Alt key and clicking and dragging the audio portion back to where it was to align it with its video again and become linked to it?
There used to be a feature in earlier versions of Premiere Elements called Sync Linked Clip which has not worked in a long time in spite of its inclusion in older Premiere Elements version Help PDF. The following is the current Adobe document related to what you are describing
As a supplement to the discussion in progress, please see if any of the above applies to your situation for a quick fix.
Oh A.T.Romano - you are a life saver! Holding down the Alt key + dragging
the audio back to the video worked, you have saved me so much work, Thank
It was more straight forward in the days when the Sync Linked Clips worked the way it did when it was first introduced in earlier versions. But for now that improvisation worked for me and glad it worked for you.