In my Fedora 38 system with plasma 5.27.11-2 my Dolphin layout has a Terminal window at the top going across the width of the window, with “Places” below and on the left and the icons window below and to the right.
On my newly installed Fedora 40 system, with plasma 6.0.5-1, the terminal window is at the bottom, and however hard I try, I cannot get it to the top, where my eye has been trained for many years to look for it. I can “Unlock Panels” and drag it, but I can never get it to “dock” at the top of my Dolphin window.
The screenshot show the desired (old) layout. As a new user I can only post one image, but the new layout simply has the terminal at the bottom, as described.
Dunno about plasma 6, but in 5, the only way to get the terminal to the top ( at least, in my case), was right-clicking an empty space in the locations panel and unlock/lock from there.
It was hard to figure out for me (Plasma 6) - I discovered I can do this if I first drag it above places, hold and wait for the drop area above that to change color, then drag it directly to the right to be able to open the drop area at the top.
In Nemo you have the same issue on 6, just vice versa. nemo-terminal (the package name) appears up top as it is default. Just theres no settings entry anymore to move it below. Maybe still editable in a config file, but I think the missing setting is a bug to be fixed.