Can't use Synapse to adjust mouse settings anymore

I have a Death Adder Chroma that up until recently I have been very happy with. The mouse works, but I can’t customize the speed anymore, and I can’t figure out what to do. I have spent probably an hour going in circles on the Razer website trying to figure out where I can adjust the settings for it. I’m using it on Windows 10 and it’s working, but I need to slow it down to make it usable for me, and I can’t find any guidance. The website support for that mouse links to a page that says to install Synapse 3, but when I open that, it says the mouse I have attached needs Synapse 2, and opens that, which then tells me no compatible device is installed. What now?