The role of godparent is an important one in the Catholic church. There can be up to two godparents, a male and a female, for a single child. The role of godparent becomes official upon baptism of the child in question. There are many reasons why it might be necessary to change a child's godparent, such as the chosen godparents moving away or even dying.
Speak to the people you would like to be the godparent of your child and find out if they are willing to take on that responsibility. Also, confirm that the former godparents no longer are capable or interested in the role.
Have your child baptized by the Catholic church with the new godparents present during the ceremony. This is only possible if you are changing the godparents before the baptism, because a child cannot be baptized twice. If your child has already been baptized there is no way to change the godparents in the church's eyes, unless the child has not received the Sacrament of Confirmation. However, you can legally change the godparents.
Explain to the church that the original godparents are no longer part of the child's life and have the new godparents present during the confirmation. They will then be listed as the godparents. If the child has been baptized and confirmed there is no way to change the godparents in the eyes of the church.
Legally, you can draft a will naming the new godparents as the caretakers of your child should you die. Let the potential godparents know about the will.
File the will with a trust or lawyer. Should you pass away, your offspring will be the legal responsibility of the new godparents.