Select the text field to make dynamic
from the Text Field pop‑up menu.
Click the lightning bolt icon beside the Set Value To
box, select a data source from the list of data sources, and click
OK.
The data source should contain textual information. If
no data sources appear in the list, or if the available data sources
don’t meet your needs, click the Plus (+) button to define
a new data source.
PDF (adobe.com)
