abraham granit

use lagacy instead of.

you should be able to fully type multiple characters in a callout

for example, when using the "basic" style rectangle callout, if you double click the default text in the canvas, after giving the object the focus, the default text should all be highlighted; then just type as usual; on some systems, they may be a lag between characters showing

are you not seeing the blinking cursor?  try a different callout color for better contrast

see https://www.screencast.com/t/gjFyRoOm8i

or, contact free tech support if issue persists