Checked a box by mistake on pension section need to change info?

Which box? Where in the program?

To change a 1099R go to 

Federal Taxes Tab or Personal (Home & Business)

Wages & Income at the top

Then scroll way down to Retirement Plans and Social Security,

Then IRA, 401(k), Pension Plans (1099R) - click Start or Revisit

FYI - If you edit or review a 1099R it does not keep your answers from before but resets them to the defaults. Then you have to go through and answer them all again.   So be sure to go all the way to the end of the 1099R section.  They are right unless you go back.  So you probably should go back and double check all of them.