After editing /etc/tor/torrc you must reload Tor so your changes take effect. (Note: if after completing all these steps and you are not able to connect to Tor, you have most likely done something wrong. Go back and check your /etc/tor/torrc and redo the steps outlined in the sections above. If your are able to connect to Tor, then you have completed your changes correctly.)
For Qubes-Whonix, complete the following steps:
Qubes App Launcher (blue/grey "Q") -> Whonix-Gateway ProxyVM (commonly named 'sys-whonix') -> Reload Tor
For graphical Whonix-Gateway, complete the following steps:
Start Menu -> Applications -> Settings -> Reload Tor
For terminal-only Whonix-Gateway, press on expand on the right.
Complete the following steps:
sudo service tor@default reload
Check Tor's daemon status.
sudo service tor@default status
It should include a a message saying.
Active: active (running) since ...
In case of issues, try the following debugging steps.
Check Tor's config.
sudo -u debian-tor tor --verify-config
Should show something like the following.
Sep 17 17:40:41.416 [notice] Read configuration file "/etc/tor/torrc".
Configuration was valid