Cursor suddently sticks to back and next controls

I created a scene in storyline where I added several separate MP3 videos - each video is embedded into a slide and the trigger to play the video is the 'Next' button in the player.

Here is now the issue: I added the progress bar for the slides with the videos and did hide the 'Back' and 'Next' buttons for thoses slides... unfortunately when I now play the video and advance it by moving the progress bar to the end - the divider slide comes up but for some reason the controle stick to my cursor... whenever I move the cursor,  it moves the next viodeo up and down and you essentially cannot selet anything anymore  and back and next seem not to work properly anymore

Is there anyone in this formum I could showcase the issue to via screen showcase who can then maybe provide tips on how to solve this issue  - should I not hide the 'Next button'? is there a different way of showing the progress the video makes when it plays (otherwise trainees will not know how long the videos take)?

Any advise is highly appreciated as this a time sensitive project.