you normally don't want to do that, and you also cannot typically do that, the option is greyed out if there is a connection to the Signal service.
These proxies are for situations in which this connection is impossible, like it's currently the case in Russia or Venezuela. If that is not a situation at play, there is no need for a proxy.
But Signal is generally putting in a lot of thought into censorship circumvention. They have been doing domain fronting in the past, but their…