Image Size and Reolution

[camjam]

I was trying our some free actions and some how, I messed up my setting in Photoshop. I normally size most of my photos to 5x7 and make sure the resolution is 300 or higher for printing. Depending on the quality of my image the resolution use to fluxuate as I set the document size. Now the resolution is set to 300 and does not change.

How to change this setting back?

Thank you