Tuition and education amounts can only be transferred to parents or spouse in the year that the tuition was paid. Carry forward amounts can only be claimed by the student. If you forgot to transfer amounts to your parents in the 2016 tax year you would have to amend your parent's return for 2016. This can be using their My Account at CRA. The link below gives information on how to change a tax return.
https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/change...