Reminders no longer move to the top when you uncheck them? I'm hoping that I've just got a setting set wrong somewhere or something.
For years I've used the Reminders app for various things but one of the most regularly used is a shopping list.  Our household tends to pretty much always buy the same things, so basically at this point I have a list of everything we ever buy and I just go into it and uncheck whatever we need, do the shopping, and check stuff off as they get bought.  Anything I uncheck, automatically popped up to the top of the list and stuff maybe we stopped buying, would gradually move down the list further and further.
I recently upgraded my iPhone SE from iOS 12.x to iOS 14.4.2.  I hate upgrading because you can't roll back if you don't like it, but there was an app I needed to use that required a newer OS.  And now I've run into this problem with Reminders.  They now seem to remember their placement in the list so that when I check off an item, it disappears back down into the bowels of the list wherever it came from, and becomes hard to find again.
This has made Reminders basically useless for me and has me thinking I'll need to turn to a 3rd party app for something so simple and basic.  Hugely disappointing since it's always worked great, until this nonsensical change.
Is there any way to gain the old behavior back again?
I had the same issue going to iOS 14, but there's actually a good reason: Reminders now has a few different sorting options to choose from, and the default seems to be ‘manual’ which won't do what you (or I) want.
To always keep unchecked items above completed items:

Open the list of items
Choose the ellipsis menu from the top-right
Tap Sort By
Choose Priority
Choose the ellipsis menu again
Tap Sort By
Choose Highest First