The scope of lightning channel charges

No, only the third case is affected. And the reason is that the channels are actually bidirectional and have two pricing policies depending on the direction in which they are used.

For example, the AB channel has a Node A policy and a Node B policy. If B increases costs – this will only affect payments from B to A, not the other way around.

This means that scenario 2, in your case, is still controlled only by node A. Scenario 3 includes payment from B to A, so the fees will be higher. Scenario 1 may also be affected by node B, but it will be necessary to increase the taxes on the BC channel and not on AB.