Whenever one or more frames are selected on a page (images, shapes, text), purple guidelines will appear to help these be positioned on the page relative to each other. The lines are are snap guidelines. These behave magnetically - when you move one frame near another frame or near the page margin lines, they will appear to guide the edge alignment and snap frames together.
To bypass the magnetic snap guidelines, hold the shift key on your keyboard while dragging the selected frame(s).
Repositioning groups of frames on your page
Reposition items on your canvas as a group relative to each other and the canvas. First, multi-select frames dragging over the area, or hold Ctrl (Windows) or Cmd (Mac) and select each item individually into the group. Note that this works for any combination of photos, elements, text and shapes.
Click on the Alignment option over the canvas.
Use horizontal alignment relative to the canvas edge.
Use vertical alignment to reposition the frames relative to each other within the group.
You can also distribute the selection relative to itself as a group to keep spacing consistent between items. Note that the items cannot be initially overlapped.