Most people wear cassettes unevenly by spending different amounts of time and load on various sprockets. Meanwhile the chain is wearing also. So very often the chain will be noisiest not on the sprockets that are used the most, but on the ones used the least.

The pattern can reverse when a new chain is installed. The new chain will run better on the newer sprockets and worse on the more worn ones.

Before we can commont on the specifics of your problem, we'd need to know which sprockets you use the most, and also which one see the hardest use. For example, I spend the most time riding the 2-4th sprockets (from high) but the 5th gets rough use, because it's the one I tend to use when sprinting some of the short steep hills I climb when I'd rather not downshift.