Audacity 2.1.2 theme problem

Operating System: Linux Mint 18.3
Audacity version: 2.1.2
Audacity installed from Software Manager
So I tried to change default theme thru adding to audacity.cfg these strings:
Then I added a “Theme” folder to the “~/.audacity-data” directory and put there an “ImageCache.png”. So then I opened the program and nothing happened in Edit > Preferences > Interface. I’ve got only crush the standart interface of buttons.