This setting can only be edited by an admin. Access to branding to edit a theme is available from plan essential.
To customize the appearance of the documents to fit your needs you can create themes.
Go to Settings > Branding and click the Edit Theme button.
Once clicked, you will see a New Theme button in the top right. A window will pop up asking you where you can edit the following at the moment:
Background type, fixed or scroll
Sign button text
We recommend using a high-resolution picture for your background image. When finished, click Save and close the window.
To use the edited theme, go back to Settings > Branding and click on the theme. You can choose standard themes or your own created ones.
The theme you choose will affect all send-outs that all users do on the entity.