So I was just paying on my world on minecraft PS4 and I noticed my anvil was acting strange. When I put my sharpness 3 pickaxe in the anvil and have a sharpness 1 book combined, the sharpness wouldn't increase, it would still cost like 3 levels like normal except the pickaxe comes out the exact same. Same thing goes with if I put in any higher level sharpness books with it. The same thing happened with my sword, it has sharpness 3 but when i try to combine it with a sharpness book it would stay the same. Except the sword was slightly different, if i put in a sharpness 3 book with my sword the sword will come out as sharpness 4... This goes with most tools and weapons I've tried enchanting, they work if they're only like level 1 enchantment but once they get to level 3 enchantment they fail to combine with books. I'm just really confused because I don't think this is supposed to happen, and if someone could tell me why that would be great.
Also I know I'm posting this on the java edition section, but this has the most views by far and I really just want to get this sorted out.
This is normal (aside from pickaxes having Sharpness, which should not be possible in survival mode, unless you meant another enchantment) - to upgrade an enchantment you need to combine it with another enchantment of the same level:
For each enchantment on the sacrifice: If the target has the enchantment as well... and the sacrifice level is greater, the target will be raised to the sacrifice's level. and the sacrifice level is equal, the target gains one level, unless it is already at the maximum level for that enchantment. and the sacrifice level is less, nothing changes on the target.