how can I move titles from "recently returned" to "completed" on MyOPL shelves?
It's actually pretty easy, and there are a couple of ways to do it.
You can always look at your recently returned list and click on the little purple plus sign to the right of the item listing that is labelled "Add to My Shelves." When you do that, a little menu will pop up and you can choose from 'Completed,' 'In Progress,' and 'For Later.'
Another easy way to add something to your completed shelf from your recently returned list is simply to rate it from 1 to 5 stars. This will automatically move it over.
Note that actually everything will stay on the recently returned list as well. If you look at that list, anything you've put on your other shelves should be noted as such where the purple plus sign used to be.
I'm glad you're enjoying the new system - thanks for your question!