Retirement tax questions

Really frustrating... REALLY frustrating, REALLY FRUSTRATING.  I wasn't sure whether to check 'simplified" or "General" method on my 1099 from OPM, so originally I checked 'simplified' and then found it was NOT simple, so I went back and changed it to "General", but now, whatever I do; when it comes up for review; the simplified

form is the one which keeps coming up in the window and It keeps asking for information I do NOT have.  I retired from civil service in 2007 and have been getting pension ever since.  PLEASE HELP.