Permalink not changing

I have been trying to change the permalink of my posts on my website . I unknowingly published my website without checking the permalink settings. After that, I tried changing it many times tried multiple methods but still not effective. Kindly help. Thanks

• This topic was modified 5 years, 6 months ago by Yui. Reason: redundant link(s) deleted

The page I need help with: [log in to see the link]