How to change FROM address in e-mail forms / templates

I would like to create e-mail template / forms where the default FROM is our group mail address.

My team is working from Outlook with both a shared team mailbox and their private mail accounts. For recurring standardized e-mails we created e-mail templates / forms accessible through 'Choose form' button. They should by default be sent from the group mailaddress. However default is the private mail address when opening a template. Even if the template was initially created and saved with the group mail address as FROM.

Does anyone know how to fix this? Thanks!