The chronograph/stop watch is activated by pressing the pusher at the two...the pusher at the two also stops the chronograph.
The pusher at the four Is only to be used to reset the chronograph to 12...this should reset the three hands ..but most likely two hands (the big hand and the sub dial minute hand at the three.
I dont recommend running your chrono over a hour...so the hour sub dial hand at the 12 should not be a issue.
If you push the reset pusher at the four while your chronograph Is running...you could very well damage the movement....remember...the pusher at the four Is only to be used to reset the chronograph....nothing else.
Personally... I wouldnt mess with these functions to much...unless you have It properly serviced.
If your watch is not working as described above....contact the dealer like KalenKong suggested.
Good luck.
Mike