I resized mine by going into my picture folder and RIGHT CLICK on the picture, select OPEN IN PAINT, once Paint opens up, I select IMAGE from the tool bar, and then select RESIZE/RESHAPE. Once the dialog box opens, I type in 80% and 80% in the horizontal and vertical box and then save and close.
I had to do this for each picture ... took a few minutes... but once I had them all done, I could then go into QB and upload them no problem.
One thing to note...when PAINT opens up, your picture will look HUGE...don't worry about it, just click on the IMAGE and then RESIZE/RESHAPE and select the 80% and 80% for horizontal and vertical RESIZE feature...don't put anything in the RESHAPE ... leave those at 100%.