Hello @JohnB738 ,
You can either use the legacy landing page sign up form, or rely on your contacts using the Update Profile form in your footer to have them update their list memberships.
To find the legacy landing page sign up form, edit it, and grab its share URL, navigate to the Sign up forms tab in your top navigation bar. Then select Basic Landing Pages. It will be the default Sign up form option on that page. Any lists you have checkmarked will be available options for contacts to select which lists they want to be a part of. Any lists you don't checkmark won't be visible, and thus contacts won't be able to choose whether or not to be on those lists. Any lists your contacts need to be on, by default of being subscribed to you, shouldn't be checkmarked.
The Update Profile form is an available footer option that contacts can utilize instead of wholly unsubscribing from you. If you have it enabled in your account settings, the UP link will be visible and accessible by your contacts. Similar to the legacy LP, any list options you want visible and selectable by your contacts needs to be checkmarked. These list selections will also be available if a contact clicks the unsubscribe link, as an alternative to confirming their unsubscription, in case they only wanted to be removed from a particular list.
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