I CAN'T UPDATE MY MID 2010 MACBOOK

That is because your MacBook is too old to run the new macOS versions. There are ways to get around this, but I would not recommend them, because they usually result in instability of macOS. I would recommend using a different browser such as Opera, Google Chrome, Microsoft Edge, etc.

The mid-2010 MacBook without the AIr or Pro moniker is only able to upgrade as far as 10.13. Safari is the only current browser not capable of running in High Sierra. Apple support is only current on Mojave and later.