Reduce double faults (volleyball)?

I play setter but been playing that position for just a year, and i keep opening my hands too wide when setting, and because of that i keep getting a lot of double faults. :/ i know i have to bring my hands closer when setting, but everytime i contact the ball my hand my hand just automatically pulls apart from each other. Its like a habit already. :/ Are there any like, techniques of training that i can use to get rid of this bad habit? :/