@Babs06   are you entering dividends for Schedule B   or  sales for Schedule D ?    

For Schedule B:   while on the Payers name line - double click to open additional information worksheet, Section B  has federal withholdings entry line

For Schedule 😧   Select Sched D, then use Quickzoom for 1099-B worksheet, scroll down to Quick Entry Table, double click while on Property Description to open additional information worksheet, scroll down to Part IV for federal withholdings