If your program is Photoshop Elements (photo editing), you have posted in the wrong forum. Somehow your thread got posted into the Adobe Premiere Elements Forum (video editing).
Please re-post your thread in the Adobe Photoshop Elements Forum or wait for a moderator here to see your thread here and move it from here to there.
You may want to check out the following Adobe document on troubleshooting your type of issue
By the way, what version of Photoshop Elements are you using on Mac?
Thanks for your direction