Some auto-response text messages can be edited. Others cannot.
Messages that CAN be edited:
One-Time Response messages can be edited. This means any SMS Messaging keyword you have set up on short code 51555 can be fully customized.
To create an SMS Subscription Keyword, click here.
Messages that CANNOT be edited:
Fundraising and Engagement (41444, 91999) and Crowdfunding (71777) automated response text messages cannot be edited -- only the Organization Name and Short Name contained within them can be changed.
You can turn off the reminder messages, though.
To customize Organization Name and Short Name, click here.
To modify which automatic reminder messages are sent, click here.