How do I stop "My Pictures" from defaulting to PhotoSuite?

if you mean all the jpg files are opening with Photsuite,you need to change the file association,so it opens with whatever softare you want.You can find how to do that by clicking on help in windows,and search for associations

In any folder, go to tools, options, file types. Select the file tupes you want (.jpg, .gof, etc) and change 'Open With' to whatever you want.