You get 4 FX engines on the CQ18. You can use them in shared or inserted mode. In shared mode you are sending multiple channels to the FX as a bus so all those channels, being sent, share the same FX settings. So, yes, in this mode, a change in any FX1 parameter would effect the sound for the other sends as well.
If you use inserted mode then an FX channel is inserted on a single channel only. So a change only effects that channel.