Image
Adjustments.
Make sure that when you change the image resolution the pixel size doesn't go up. If it does you need to change one of the checkmarks at the bottom, I forgot which one it is... its 1:38am here, if you can't figure it out pm me and I'll check when I get online tomorrow.
Also if you can't figure it out and you want an even faster fix go to File
new document and make sure the resolution is set to 72 pixels per inch or dots per inch, once it is choose your canvas size (signature size) and create it. Then drag your graphics off of that .psd into the new one. Try typing there it should work. (Your graphics may get really small or REALLY BIG so don't be surprised)