This is my method for getting the right size to upload.
Once I get the pictures from camera to laptop and put them into pictures file with a name I can recognize,,, I open the picture I want. Crop it so background clutter is removed. Save that. Then with file open, up on the right corner of the computer or picture screen is a symbol of 3 dots, stacked on top of each other. Click it. Click "resize". Click "2mp". Save with new name, I usually add 2mp to the name of the file. Close everything and go back to posting on QB. Be sure to use the red reply button, not quick reply.