There are two different parameters with Embedded Templates that have to do with signers, but serve different functions.
allow_edit_signers is a parameter in the Create Embedded Template Draft endpoint, that when provided and
True, lets you edit the signer roles in the editor’s righthand sidebar. You must select a field to show the sidebar.
force_signer_roles is a parameter in the Get Embedded Template Edit URL endpoint that when provided and
True, shows a modal to edit signer roles before showing the editor.