KDE problems (sound and display)

Hello everyone.
I am running Pop_OS! 21.04 with KDE installed (i hate Gnome, even if Cosmic looks great)
I’ve had problems with Pulseaudio and my bluetooth headset (disconnecting all the time) so I’ve switched to Pipewire and now the BT works fantastic. The only problem I have is that now I can’t use my normal speakers anymore (line out) as I can’t switch between outputs. I can go on KDE settings and activate the proper output, I see the bar moving as if it was playing but actually nothing comes out… (and i do the right-click play all audio via this device) Any idea how to solve this?
Secondly I have a 4k monitor, and a second monitor on the side that is 1080p. The scaling is atrocious and i can’t figure out how to set the proper scaling on each display. It seems that the problem comes from Xorg but I’ve been searching on the internet for a while, and i don’t find any solution for KDE (on Gnome apparently we can use the fraction option and play with that). Did someone find a solution for that?
Thank you for your help!

I’ve found the solution regarding my pipewire issue: I’ve had to add
systemctl --user mask pulseaudio then reboot and it works now like a charm. For the display it’s still messy though…