Site construction URL sometimes shows up in our visitor's browser address

When we we're creating our Squarespace page, Squarespace created the following URL for the site in construction: https://jeff-blom-k53z.squarespace.com/. 

When the design was completed, we migrated it over to our custom URL. However, strangely, when people use certain of our forms, the results shows up on the site construction URL, https://jeff-blom-k53z.squarespace.com/, rather than our custom URL, peacepilgrim.org.

How do we make sure that our construction URL never shows up on our visitors browser address?. We would just as soon never use the construction URL for anything but we don't seem to be able to get rid of it. Any help would be appreciated thank you

What is your custom url? We can check your site using it and see if the internal url shows up. You can change that url  to  xxx....squarespace.com if you wish, and the old one will eventually stop working.  . 

Our custom URL is:
peacepilgrim.org

The url used during construction of the site, which pops up when using certain forms, is: 
https://jeff-blom-k53z.squarespace.com/

Thank you for your help with this.

I viewed all your pages and as many links as I could. The internal URL never appeared.  I could not find a form with the internal address either. I think whomever is seeing that address may have it in their browser history or bookmarked and that is how they are getting to it. Once they do, it will stay in the address bar on any link unless they change to the custom domain. If you entered it, it most likely would change to ....../config. As I mentioned you can edit that domain, which is also your site ID, and change it to another .squarespace.com ID. It will stop it from working for anyone who has it in their history, and if they use it "No Such Website" will show up on their screen.