I was having so trouble with decals, I decided to follow this.
It helped my issue, but when I reloaded the project all my textures were low res and very blurry.
I’ve since reverted the changes I made and reloaded but my textures are still low res and blurry.
It most likely automatically lowered your setting because of a huge performance demand in the project. go to settings and change setting to high under scalability. Hope that helps.