Can't change page links

Hello,
I make a post for by home page (the first page without https://www.example.com/…) And if i want edit the post then it will coming this. https://www.example.com/registration
But on my permalinks settings, i have set this to Custom Structure because i want like https://www.example.com/registration
All the page that i have maked i changed the url like /members, /forum…
Only if i create i post of edit a post then it will set to /registration automatic.
I can’t edit the link.

Anyone will help ?