In PowerPoint align objects so they look more appealing and use the PowerPoint order of objects feature to rearrange them how you want.
Sometimes you may want to group multiple objects into one object so they will stay together if they are moved. Often, this is easier than selecting all of the objects every time you want to move them.
Pictures, shapes, clip art, and text boxes can all be grouped together, but placeholders cannot be grouped. Therefore, make sure not to insert your pictures into placeholders if you will be grouping the pictures.
If you select the objects and the Group command is disabled, it may be because one of the objects is inside a placeholder. If this happens, try reinserting the images or cutting and pasting them into the same slide outside of any placeholders.