Hi, Andrea.
CW signal in RX mode has very narrow bandwidth - near 1 Hz.
At the same time, RX EQ has too wide bandwidth for each slider, that's why CW signal can be influenced by only one EQ slider, from 18 available, which basically means a simple gain of the signal i.e. you are making this signal louder or weaker. You can do the same with the Volume knob or APF. APF amplifies signal exactly on the tuning frequency, lower gain on the edges (filter with bell-like AFC).
APF bandwidth depends on two parameters: Quality and Gain (Options-> Device-> DSP-> DSP).