How to play those bars? (Bach)

[3022767]

Hello everyone  

I've attached a picture of bars 7 to 10 of Bach's Prelude number XVI (WTCII) but I have a problem playing bar 10:
I know that all the si should be played in bemolle but the si becomes normal on bar 8. Does the normal sign only affect the si on bar 8 or should I keep playing normal si in bars 9 and 10? I'd like to know if the chord si/re bar 10 should be played si(normal)/re or si(bemolle)/re.

I know it might seem a silly question but I don't understand how long the normal sign on the si lasts...  

Thank you in advance  

[tdawe]

It lasts only for 1 bar.
It also applies only to that exact pitch. For example, if my key signature calls for me to use C-sharp, and the score indicates a C natural at middle C, the C an octave above would still be played as a C-sharp. The next bar, as long as the score does not indicate another accidental for C natural, all C returns to being C-sharp. Sometimes the composer will indicate the return to C-sharp in the score, especially if there has been an extended use of accidentals, but even if they do not, you still return to the key signature when a new bar begins.

[3022767]

Thank you very much for your help  everything is clear now!