I just noticed on my Macbook Pro, there is a 12GB storage difference between what "About This Mac" says and what my "Downloads" folder says. Here's an image of what I mean. Which one shows the correct amount and how do I fix this problem?
You are missing 12GB? That is probably the Backups -- snapshots on your internal drive that can be overwritten if needed for something else. Maybe it is time to connect your Time Machine drive and do the regular backups.