If your program is Photoshop Elements 12, you have posted in the wrong forum. Your thread has somehow been posted in the Adobe Premiere Elements Forum (video editing).
Please repost 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.
Much has been written about Photoshop Elements 12 on Mac Yosemite 10.10 and the good people in the Adobe Photoshop Elements Forum should be
able to advise you with the best information possible on this matter.