In Photoshop when you finish a image that you are working on and begin a new document you should in most cases reset your preferences. This sets all of your tools and pallettes back to the default settings.
This is particularly important if you are prepping an image for the yearbook and then switching to work on an image for video.
To reset your preferences: Hold down Command-Option-Shift as your launch Photoshop.
A message saying "Delete the Adobe Photoshop Settings File?" will show up