Domain switched and now issue

HI guys, So i had installed WordPress on a .tk domain and then follow this
https://codex.www.ads-software.com/Changing_The_Site_URL

but now when i remove this code

update_option(‘siteurl’,’https://example.com/blog’);
update_option(‘home’,’https://example.com/blog’);
(modified for my domain)

from the config it trys to go to mydomainname but it then goes /blog/whateverurl and it always gives me a 404.

Even if i save the settings with the code in the file and then remove it the same issue occurs.

I have tried everything i can think of and it only works properly when i leave that code in the config file. Is it required to stay in the config file permanently now?

I use WordPress as a CMS for my tech website so…. Id like to solve this.