Dates on Forms

SUGGESTED

We have been using a two digit year and now need to switch to four digits.  We went into the form and changed the date box to show XXXX instead of XX as it was but now when the forms print, it prints XXXX and no numbers at all.  Any suggestions?  Also, can you add a field on the sales order/invoice to show the line of credit on an account? I appreciate any help that can be provided!