There's not a way to change it on an individual level.

As far as I'm aware / heard, when an instance has it disabled, it doesn't even store information (or process) downvotes, so even if you could override it (such as by using a third party client) there'd be nothing to view.

I could be wrong though, might be worth trying some of the mobile apps to see if it displays it, just to confirm. For desktop, there's also Photon.

I personally find a lack of downvotes to be annoying and harmful. People don't go through the trouble of reporting problem content, and it usually leads to poor quality inflammatory content rising to the top.

If you're new and haven't really set up yet, explore other instances. You can find one that aligns with what you want out of Lemmy without jumping through hoops.

If you have set up, there are account migration tools for you. They just aren't perfect yet