Pic 2: ......and this happens! Wonky polka dots! Remove your paper and start with a clear slide.
The solution (in most case) lies below!
Pic 3: .....Go to 'insert', 'shapes' and 'rectangle'
Pic 4: .....and draw yourself a snazzy rectangle.
Pic 5: .....click on 'format'.....
Pic 8: .....find your file and insert the paper you wish to use.
Pic 9: You can see in the pic below, it now looks like it did originally - out of shape, but remember we have encased the paper in a shape, so we can format it. Right click on the paper, scroll down to 'format picture'.
Pic 10: Select 'fill'.
Pic 11: Check the box 'tile this picture as texture' and you will see your paper change shape!