Redirect forms to Thank You pages

Are they for different roles? If so, you can edit that role (Ultimate Member -> User Roles) and change the “Action to be taken after registration” to point at your Thank You page for that form.

In that case, you need some code either in a custom plugin or in your theme’s functions.php file.

function my_redirect_after_registration( $user_id, $args ) {
    global $post;
    # grab the name of the page the form was submitted from
    $slug = $post->post_name;
    if ($slug == 'your-registration-form-1') {
        # get the page we want to redirect to
        $posts = get_posts(array('name' => 'slug-of-page-you-want-to-redirect-to', 'post_type' => 'page'));
        # grab the permalink to that page and redirect to it
        exit(wp_redirect(get_permalink($posts[0]->ID)));
    } else if ($slug == 'your-registration-form-2') {
        # redirect to a specific URL instead of a page slug
        exit(wp_redirect("https://some-specific-url/"));
    }
}
add_action( 'um_registration_complete', 'my_redirect_after_registration', 10, 2 );

Note that if you use auto-approve, this will pre-empt the approval process. There’s no other appropriate hook I can see to use when you’re NOT doing auto-approve though. If you are using auto-approve, you’ll want to hook um_post_registration_approved_hook instead of um_registration_complete, and set the priority (the 10 in the add_action function) to something higher than 10, like 20 or so (because UM uses its own hooks internally, and the *real* auto-approve code runs at priority 10, and you want it to go first before it runs yours)

Probably worth a different topic for that just to help other people find it if someone else runs into the same problem. I’m not sure what I’m looking at in your videos though (start a new topic before expanding on that idea though).