Moving an image saves straight away. About half a second after you drop it, the new order is stored and the message Media order saved appears. What it does not do is change what visitors see: your public project page keeps the order from your last publish until you publish again. The same save also puts the project back into Draft, which catches people out when they only meant to move a picture.
That is the opposite of the rest of the editor, where a title, a description or a newly added image sits in a draft until you press Publish. What the project editor saves on its own sets out which changes wait and which do not.
The gallery is the order
Where a tile sits in the gallery is where that image sits on your public page.
- Drag a tile to where you want it, or use the up and down arrows in list view.
- Stop. The order saves on its own about half a second later.
- If the save fails, because you no longer have edit rights for example, the gallery snaps back to the order it had and an error message appears.
Your cover does not move
The cover is the first image, and it sits above the gallery rather than inside the strip you drag, so rearranging the other images does not change it.
To change the cover, open an image and tick Set as cover image. That moves it to the front and goes public at once, the same as any other reorder. A video cannot be a cover, so the option is not offered on one.
There is no undo on order
Nothing on the page puts the previous order back, and the snap-back above happens only when a save fails. Version history is written when you press Publish, so an earlier arrangement can be recovered only if it was published: see Restoring an earlier version of a project.
Press Publish before you leave
A reorder also starts the ordinary autosave a couple of seconds later, and that opens a draft, so the status chip can read Draft even though the change is already public. Press Publish at the end of any session where you moved images, so your draft and your live page agree.