where to edit add/renew link in amember/member page?

I want to create a custom signup page in forms editor and link it inside amember/member, to the button add/renew subscription. But I don't know where to edit the link? Anyone knows?

thanks

You control which signup form is displayed in the "Add/Renew" tab of the Members page from the Forms Editor homepage. Create the new form and click the radio button in the "Default for Member" column as shown in the image below.