permalinks (please help!)

Hello:
i’ve recently created a subdomain for blog. i.e. https://blog.mysite.com. before it was https://www.mysite.com/blog. after changing changing the subdomain, i’ve decided to create permalinks for all my links.

i selected Permalinks under Options. and one of the options that i chose is “Date and name based” >> https://www.mysite.com/blog/2006/03/05/sample-post/

however, it should be https://blog.mysite.com/2006/03/05/sample-post/.

i couldn’t seem to change the URL in Permalinks so that it recognizes the new subdomain.

my blog currently runs fine using the subdomain structure.

please advise how i should configure Permalinks so that i can run in the subdomain format. i appreciate any insights.