Will I be held accountable for child's truancy if child no longer lives with me, as divorce decree wasn't updated?

Divorce decree around 5 yrs ago gave me main custody of the kids. Had issues with the 16 yr old being truant at school and ex wanted to step in. Verbal agreement that he has custody of the 16 yr old. Child has been living with ex for over a year now. Kid is also VERY truant at his new school. If something happens pertaining to the frequent truancy, would I be held accountable since the written decree states that I am to have custody of the child? Will the truancy from the previous school be counted and hurt me somehow? (School told me it doesn't carry over from school to school, only continues if child moves back in with me).