These are little-used settings that have not seemed worth creating specific UI for.
You can manually edit PSP/SYSTEM/ppsspp.ini in your memstick directory to set these.
To find the location of your memory stick on your device, navigate to Settings -> System -> PSP Memory Stick -> Show Memory Stick folder.
Nice copy-paste-able lines below:
[General]
TopMost = True # keeps PPSSPP in front of other windows
PauseWhenMinimized = True # pauses emulation when PPSSPP is minimized to the taskbar
ShowMenuBar = False # hides the menubar from the window
# use these to set the window position and size pixel perfectly
WindowX = -8 # -8 to offset invisible window edge in Windows 10
WindowY = 0
WindowWidth = 1296 # +16 to offset invisible window edges in Windows 10
WindowHeight = 720
[Recent]
MaxRecent = 0 # hides the Recent tab