There are 3 basic scenarios when you want to modify default settings:
In any case you will have to make changes to the setting files in ~/.kde or ~/.kde4 or /usr/local/share or /usr/share.
When a new user is created, the content from /etc/skel is copied to his home directory. If you want to change the settings for all future users, just change the files in /etc/skel.
To change the default browser, use the program System Settings. However, there are situations where you cannot call kcmshell5 to open System Settings. In this case you can use the following script. It changes the default browser to Firefox:
#!/bin/bash # This file sets up a computer as tstaerk likes it. Call it after you have performed the OS installation.
# 1. set default browser to firefox # 1.1. for SUSE Linux, where we have to look in .kde4 instead of .kde # The key for default browser is BrowserApplication. cd cd .kde/share/config # first delete all the old entries for BrowserApplication sed -i 's/BrowserApplication\[\$e\]=.*//g' kdeglobals # add BrowserApplication to the General section if a General section exists sed -i 's/\[General\]/\[General\]\nBrowserApplication\[\$e\]=!firefox/g' kdeglobals # add a General section and the key BrowerserApplication if no General section exists grep "\[General\]" kdeglobals || echo -e "\n[General]\nBrowserApplication[\$e]=!firefox" >> kdeglobals