That statement may or may not be correct depending on how certain key words are intepreted, but taken at face value it sounds like a common misconception about "delayed choice quantum erasure". Half the articles I see on that topic make steam come out of my ears, because I know they are feeding that false impression. Nothing that an experimental setup does later can alter the correct prediction of a prior outcome. It is only our interpretation of when things happen that tends to be faulty-- our intuition about causality, not causality itself.
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could you explain a bit?

as i understand it if you know the path the pattern goes....

if you measure after the slits ie know the path the pattern goes...seeming to suggest that the photon took one slit or the other....tho it does hit the detector after...

i get very confused with all those mirrors...

please dont misunderstand me i am not into this whole observer thing and completly agree that it depends on the experimental set up...

tho why the 2 different results exist?

i must also admit to not being smart enough to have a problem with the role of observers in science...i'll leaver that to philosophers....nmp