I thought it should appear one-time, but it appears every time you start .. how do I fix it?
Did you set this download location in the past? If so, can you check what DataDir is mentioned in ~/.config/Bitcoin/Bitcoin-Qt.conf ?
One way to answer this question: enter this in a console:
grep DataDir ~/.config/Bitcoin/Bitcoin-Qt.conf
Did it ever finish synchronisation completely? I can't read the Russian text, but since it's in red: does it mean you don't have enough diskspace on that location (or on the default location)?
What happens if you just click "OK"?