I opened my Konsole window, then from Settings > Configure Console I UNCHECKED the Show window title on the titlebar and clicked the Apply button. The titlebar has been properly removed.
Right after that I CHECKED again the Show window title on the titlebar and clicked the Apply button again. From that moment I couldn’t get back the titlebar for my Konsole window no matter what I try.
I made the change and the file changed was $HOME/.config/konsolerc. When I unchecked that option the file did not contain ShowWindowTitleOnTitleBar keyword. I don’t have the option “Remove Window Titlebar and frame” checked, which is right under “Show window title on titlebar”.
If you don’t have it, you might want to add:
[KonsoleWindow]
ShowWindowTitleOnTitleBar=true
If you have it, you might want to remove it:
RemoveWindowTitleBarAndFrame=true
TIP: I have an alias, alias f1='find -newermt "1 minute ago"'
When I make a change I run this alias, so I know what gets touched. It’s educational, plus can be a lifesaver too