By default, images placed into layouts are not locked into position. You may move any selected frame on the page and apply it into a new layout. However, while fine-tuning your composition you may want to keep some images in place and design around them.
Locking an image in place
A locked image will not move when a new layout is applied, and may not be selected. Use this feature when you wish to cover all or part of your canvas with an image that will act as a texture or background, or need to keep a feature image in position.
To lock an image, select it, access its general options icon, and choose Lock, or hit the L key on your keyboard while the frame is selected.
If a new layout is applied to the area, the locked frame will remain in place. Unlocked images will move over the locked image.
To unlock, simply double-click the lock icon, or return to the general options icon.