Find a document file of the type (any file). Select it, and choose File -> Get Info 🙂apple:I). At the bottom, where it says Open With, select the program you want, and then hit the Change All button. 🙂
You'll have to do it once for each document type.
The root cause for this issue, as far as I can tell, is that NeoOffice does not make an attempt to redefine the default program for these document types for you itself.