You can only edit the default message. However, there’s no option for us┬áto add a signature (please see attached screenshot).

To edit the default message:

  1. Click Gear.
  2. Click Account and Settings and select Sales.
  3. Click Messages.
  4. Customize the message.
  5. Click Done.

If an ability to add a signature is essential to your […]

Resolution for 'Click Messages issue: 'When emailing invoices, how do I change the “Body” of the message?' available: Yes.

The Click Messages issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the Click Messages issue yourself by looking for a resolution described in the article. If it is a complex Click Messages issue or you are unable to solve the issue, you may contact us by clicking here or by using other Click Messages support options.

For more information about resolving issues related to Click Messages in Quickbooks/QBO or to get support for the issue 'When emailing invoices, how do I change the “Body” of the message?', click the link below: