things have changed when...

Hi,

Just read a composition, there is a sentence:
"Things have been changed when Mr. XX discovered this new learning system."

I am a little uncomfortable with this structure and not sure if this is all right to use perfect form " have been changed" with "when" here.

Can you please confirm.

Thanks

Wv.

Hello,
"Things changed when..." is better. It's the "have been" (implying someone did it) that's the problem because then the someone would have done it the discovery and the phrase would be "Things have been changed since..."