Issues and fixes

Possible Issues (for non-KDE users):

1. if the dialogue box doesn't automatically shows to you then you can run sudo dpkg-reconfigure sddm and set sddm there as your default Display Manager

2. if you're sure the sddm.conf file is nowhere to be found, just create a new file with text editor, copy/paste the text below in it, rename or save it as sddm.conf, put it in your /etc folder

# Whether sddm should automatically log back into sessions when they exit
Relogin=false

# Name of session file for autologin session (if empty try last logged in)
Session=

# Username for autologin session
User=


[General]
# Halt command
HaltCommand=/bin/systemctl poweroff

# Input method module
InputMethod=qtvirtualkeyboard

# Comma-separated list of Linux namespaces for user session to enter
Namespaces=

# Initial NumLock state. Can be on, off or none.
# If property is set to none, numlock won't be changed
# NOTE: Currently ignored if autologin is enabled.
Numlock=none

# Reboot command
RebootCommand=/bin/systemctl reboot


[Theme]
# Current theme name
Current=sddm-theme-amadeus-master

# Cursor theme used in the greeter
CursorTheme=

# Number of users to use as threshold
# above which avatars are disabled
# unless explicitly enabled with EnableAvatars
DisableAvatarsThreshold=7

# Enable display of custom user avatars
EnableAvatars=true

# Global directory for user avatars
# The files should be named <username>.face.icon
FacesDir=/usr/share/sddm/faces

# Theme directory path
ThemeDir=/usr/share/sddm/themes


[Users]
# Default $PATH for logged in users
DefaultPath=/bin:/usr/bin

# Comma-separated list of shells.
# Users with these shells as their default won't be listed
HideShells=

# Comma-separated list of users that should not be listed
HideUsers=

# Maximum user id for displayed users
MaximumUid=60000

# Minimum user id for displayed users
MinimumUid=1000

# Remember the session of the last successfully logged in user
RememberLastSession=true

# Remember the last successfully logged in user
RememberLastUser=true

# When logging in as the same user twice, restore the original session, rather than create a new one
ReuseSession=false


[Wayland]
# Enable Qt's automatic high-DPI scaling
EnableHiDPI=false

# Path to a script to execute when starting the desktop session
SessionCommand=/etc/sddm/wayland-session

# Directory containing available Wayland sessions
SessionDir=/usr/share/wayland-sessions

# Path to the user session log file
SessionLogFile=.local/share/sddm/wayland-session.log


[X11]
# Path to a script to execute when starting the display server
DisplayCommand=/usr/share/sddm/scripts/Xsetup

# Path to a script to execute when stopping the display server
DisplayStopCommand=/usr/share/sddm/scripts/Xstop

# Enable Qt's automatic high-DPI scaling
EnableHiDPI=false

# The lowest virtual terminal number that will be used.
MinimumVT=1

# Arguments passed to the X server invocation
ServerArguments=-nolisten tcp

# Path to X server binary
ServerPath=/usr/bin/X

# Path to a script to execute when starting the desktop session
SessionCommand=/etc/sddm/Xsession

# Directory containing available X sessions
SessionDir=/usr/share/xsessions

# Path to the user session log file
SessionLogFile=.local/share/sddm/xorg-session.log

# Path to the Xauthority file
UserAuthFile=.Xauthority

# Path to xauth binary
XauthPath=/usr/bin/xauth

# Path to Xephyr binary
XephyrPath=/usr/bin/Xephyr```