Best way is to disable it in settings on your phone and within google play store settings. Sadly I have moved away from Samsung as the devices are not compatible with anything in the house. (That's for another thread though)
go through to your settings and search for automatic update and switch it off.
I get an error message popping up every 10 seconds or so. It says 'Samsung cloud keeps stopping' and underneath has 'X Close app'. If I try and view photos in my gallery then a similar message appears immediately 'Samsung cloud has stopped' and automatically closes my gallery so I can't view photos. So annoying!
I have also had something suggest that my photos are not being backed up. Please help! It's almost unusable.
This happened to me some years ago. Rendered it UNUSABLE. Samsung plugged it into their computer and couldn't fix it.. etc. I ended up selling the device. The new owner could log in and it worked perfect. It has something to do with your google account fighting with the samsung account. Anyone else can use it. There are a few troubleshooting steps but even if you wipe that device, it will work for you until google play services update then it'll go back. It's a horrible loop that's next to impossible to solve. It will solve temporarily but then go back =(
After this mess, I have abandoned Samsung. We are an apple family now. I have fears that since it was with my specific account... it will happen with any other Sammy device I get.