Changing links

I would like to change a couple of links in the auction theme. I want to change the link on the front page where it says “Login” and “Register and on the “login page” where it has a “register button” it links to https://www.mydomain.com/wp-login.php even though I have changed the link to https://mydomain.com/signin

Can someone tell me how to change the url that is linked for login, the register button and the login button.

Can I edit these links from the admin panel or do I need to edit them within the theme files? If so which ones?

I really appreciate the help.

Thank you!