Theme: Text, font, multiline text
How can I change the texts in the caption field in a drawing frame?
At first place a drawing frame to your schematic page:
(Image 1: Use the sidebar icon at the bottom of the sidebar to the right)
Once the drawing frame has been placed, you can now double-click the texts to change them. Make sure that the button in the top right corner of the sidebar is switched off (see circle in the picture above). Otherwise, a double click always selects the complete circuit frame like a complete component and you cannot access its individual elements - texts in this case.
You can also find a detailed description here.