This is what I do for my A940:
1.  Click on FILE on your toolbar, then PRINT.
2.  When the little print screen comes up (before you click on Print), click on the word PROPERTIES (top right, I believe).
3.  On that screen, I always keep the radial button set on QUICK (saves ink) under the Quality/Speed column, and on the bottom right of that screen click a checkmark in the box that says PRINT COLOR IMAGES IN BLACK AND WHITE.  Click OK, then click OK on next screen to print.  You should print even color pages now in black and white.
4.  If you want, you can then go back to the FILE/PRINT/PROPERTIES, and at the top of the Preferences screen (again, before clicking the Print button), click on SAVE SETTINGS.  Click on a radial button and name it QUICK (or whatever quality you want).  Don't click on Default Settings.  Next time you to to the Print box (before printing), click on Properties and check to see if the Print Color Images in Black and White box is checked.   
5.  To print something in color, again at top of screen (FILE, PRINT, PROPERTIES), unclick/remove the Print Color Images in Black and White box.  After removing the checkmark, you can then select Quick/Normal/Better/Best for a better quality (Quick uses less ink).
6.  Bottom line:  in PROPERTIES box. if checkmark is shown you'll print in all black and white.  If checkmark is removed, you'll print in color.  Hope this works.....it does for me.  Good luck!