Just a note to everyone. Contact Samsung directly about this, I sent them an email and they do read and reply to them. Be thorough about the things you don't like, perhaps if everyone does this it might actually change things back in the next update.
Yes, bring back stacked view, put clock back on right, WHERE is split screen now???...and other issues(!)...add new more Samsung/Droid like multitask, see a lot in one view efficiency + productivity enhancing features...if I wanted a one thing at a time iPhone I'd have bought one...please fix this.
Hit the 3 lines bottom left then with the app screen hit the icon at the top and split screen is there.
Also download goodlock from the galaxy app store, you can move the clock and improve the stack view. Not as good as oreo but it's definitely better.
After 2 hours on the phone with Samsung tech, I was told there is no undo for the update. You just have to wait until they push a fix..... "hopefully in a week or two"... according to him. HA... I may be trying out my first iPhone by then, as much as I hate iPhone. I liked the Galaxy series, and have been loyal to it since the very first one, mainly because of the sd card memory jump you could get, (with the exception of the Note 5).