I'm not sure I understand your question, but I'll give it a stab. Don't set time while the chrono is running. When the chrono seconds hand (at the center) is anywhere between 10 o'clock and 2 o'clock, push the top Start/Stop pusher first, then the bottom Reset pusher. The chrono seconds, chrono minute hand and chrono hour hand will all reset to their 12 o'clock positions. The non-chrono seconds is unaffected and continues to run. Disengage the CG lever, pull the crown to position 2 (the non-chrono seconds hand will then stop in its track) and set the time. Push the crown back to position 0. The non-chrono seconds hand starts again. Done.
And you thought you were confused! [emoji1]