You can create your own text templates in the settings under “Text template”, which you can insert into your header and footer any time with a mouse click.
Just choose a name that you can remember, as well as a template type. This type defines which kind of document (invoices, estimates, e-mails etc.) the template will be visible in.
If you turn on the switch next to “Set as default”, then the template will be automatically inserted into documents.
If you turn on the switch next to “Only visible to me”, then other users won’t be able to see your template.