When updating template code or field options, a new template revision will be created. All signatures currently using the updated template will not see the changes, until you manually update them to use the new revision.
In the template detail page, you will see a breakdown of all signatures using a given template and whether or not they are using the latest revision. If there are any signature using an outdated revision, you will be prompted to update them by clicking on the Update signatures button that will appear next to each template’s name.
After updating signatures with new templates, the signature code will be changed. Repeat inserting signatures to your e-mail client to use the latest signature.