My soursop tree has a lot of flowers but it won't bear fruits at all.
Why Soursop Tree Flowers but Won’t Bear Fruit
Certified GKH Gardening Expert
This is most likely a pollination problem. Soursops in their native habitat are pollinated by ants, and will be better pollinated if at least two trees are growing nearby. Hand pollination will solve this problem. See these links for how to do it (the first explanation is for the related cherimoya tree, but the advice applies to soursop too):