Hi jannik
Certainly the Quick Tracks and Smart Sound do not appear to be installed.
Yet you say you have X4 on the same PC with Smart Sound working.???
I assume you purchased the program from Corel, some earlier programs especially downloads were supplied with two files at about 800Mb each, the full version being 1.4Gb, If you have smaller files one will be a Contents.exe file, this should be installed to complete the installation of the program.
Saying that I think X6 is one file at 1.4 Gb
Can you access the Corel Guide and Check for Updates.
Some updates may be associated with the Smart Sound installer.
The info below also refers to an installer.
After installing Quicktime 7, SmartSound no longer functions properly
http://corel.force.com/index/articles/e ... 000000L5DZ
Unfortunately I do not run Windows 8 so difficult to replicate your problem.
Using XP the installation files are extracted and saved to the C/Drive
I found the Smart Sound installation files here
C:\Program Files\Corel\Corel VideoStudio Pro X6 Setup Files\Corel VideoStudio Pro X6 Setup Files\Setup\RunTime\Quicktracks5Installer
Maybe try running the Setup.exe
I tried this and was given an option to Modify, Repair or Remove