I have followed everything but not how to change stake from nextcoin wallet to
token.
Original stake holders get stakes after beta and after this those who have
bought their stake. Was there already a plan for it?
Please read the full instructions here: https://medium.com/@xtester/nem-redemption-process-f90db6b10eef
Everything is explained in detail, even for NXT AE stakeholders. The relevant information for NXT AE stakeholders is in the section for Phase 2 in the above guide.
If you have any other questions after reading the instructions, just let me know. 