AdminCP > User Profile Fields > User Profile Field Manager > Edit About Me or whatever you call it if you renamed it > Change Single-Line Text Box to Multiple-Line Text Box. You may also want to change the Max length of allowed user input
AdminCP > User Profile Fields > User Profile Field Manager > Edit About Me or whatever you call it if you renamed it > Change Single-Line Text Box to Multiple-Line Text Box. You may also want to change the Max length of allowed user input