After modifying the original template file, re-upload the file from the target OFC_Template record page. If only the template content is changed, there is no need to change the settings for custom buttons or Lightning buttons.
If you do not know where the original template file is stored, please contact your internal system administrator or the system vendor that installed the system.
The uploaded template file is attached to the OFC_Template record and stored in the Note and Attachment (Attachment) object. The uploaded template file is changed by the application for output, so keep the original template file separately.
Instruction manual