Conversation so far:
Where does the Vienna Boys Choir perform?
CANNOTANSWER.
How large is the Vienna Boys Choir?
The choir has for the first time had to advertise for recruits.
Were they able to get enough recruits to keep going?
The Vienna Boys' Choir has sought to update its image.

Question: How have they changed their image?
Self-contained rewrite: How have the Vienna Boys' Choir changed their image?