Setting a ticket to personal only affects how the replies sent via email to the user are displayed, i.e. it affects whether the user can see the agent's name, personal email address and personal signature in the email. There is no specific setting to make all tickets personal, but, as this option is only relevant for users contacting you via email, you can create ticket dispatching rules under Configuration\E-mail Settings so that anything sent to your email addresses is set to personal.