Templates are grouped by how many photos are currently loaded, so as soon as photos are added, the layouts that actually fit that count are shown first. Adding or removing a photo does not force a layout change, the suggestions simply reorder, so it is safe to upload a few extra photos to choose from before settling on a final set.
Every template is defined as a set of proportional cells, not fixed pixel sizes, so switching between square, landscape, portrait and story canvas shapes keeps the same relative composition. A big-photo-left layout stays a big-photo-left layout whether the canvas is a square Instagram post or a tall story format.
Getting a clean crop inside each cell
Most photos will not match their cell's aspect ratio exactly, so the tool automatically scales each photo to cover its cell completely with no empty gaps, then centers it. Click a cell and drag to shift which part of the photo shows. To zoom in past that default fit for a tighter crop, either pinch on a touch device or hold Ctrl (Cmd on Mac) while scrolling, a plain scroll without the modifier key does nothing. The zoom slider in the toolbar below the canvas gives the same control with a precise percentage and doesn't require any modifier key.
Swapping instead of removing and re-adding
If two photos would look better in each other's spot, there is no need to remove either one first. Drag a photo directly onto the cell holding the other photo, the target highlights in green while the drag is in progress, and releasing swaps both photos along with their individual pan and zoom settings. This only works between two cells that already hold a photo, dragging onto an empty cell does nothing, use the unplaced tray to fill an empty cell instead.