Images suddenly attached to bar while open them

Hi!

I'm still using the ancient Photoshop Elements 15 in Mac succesfully until now.  Suddenly today after opening the program all the images are attached to the bar, which I don't want. I'm used to working with images in separate windows. I always have many images open at the same time and they overlap eachother in the left hand corner of the window and they can be managed totally separately. How can I get this option back on again? I would really appreciate help concerning this!

Thanks, Mia