i already try change the value but it's keep going back to original value
It's been a long time so excuse me if I mess up. Make sure to keep separate back up saves in case you mess up.
Input the current turn number (not the turns left) into the box and search with exact value and 4 bytes. Rest and move to next day and then add 1 to next scan.
Repeat until you find the turn number value, test it out by setting it to 1 and checking the box next to it to lock it. Rest and move to the next day. If it stays at one and the "turns left" doesn't change then you probably got it right. Keep the box checked while playing as well just in case.
Like other games the values here will only apply to the current session. After you shut it down the values will change the next time you play it.