Most likely, your attempt at editing `google-chrome.desktop` didn't work because that file has more than one `Exec` directive, and the one you changed wasn't the one that is actually used.

Using the Chrome package for Debian from [Google's repository][1], `google-chrome.desktop` shows three `Exec` directives in three distinct sections:

```lang-none
$ grep -E '^Exec|^\[|^Name=' /usr/share/applications/google-chrome.desktop 
[Desktop Entry]
Name=Google Chrome
Exec=/usr/bin/google-chrome-stable %U
[Desktop Action new-window]
Name=New Window
Exec=/usr/bin/google-chrome-stable
[Desktop Action new-private-window]
Name=New Incognito Window
Exec=/usr/bin/google-chrome-stable --incognito
```

The one with the `--incognito` option—likely the one you edited—is only executed when you select "New Incognito Window" from a context menu (e.g. the application menu).

Unless your goal was to change the configuration for every user on your system, I suggest you to create your own, customized version of `google-chrome.desktop`:

```lang-none
$ cp /usr/share/applications/google-chrome.desktop ~/.local/share/applications/
```

And then edit the `Exec` directive, _at least_ in the `[Desktop Entry]` section (you may want to keep the other `Exec` directives aligned to ensure Chrome will behave the same way no matter what menu entry you use to start it):

```lang-none
Exec=/usr/bin/google-chrome-stable --proxy-server="socks5://proxyURL:proxyPORT" --host-resolver-rules="MAP * ~NOTFOUND , EXCLUDE proxyURL" %U
```

As noted by [Dominik Matis][2] in a [comment][3], you may want to add the `--host-resolver-rules` option to prevent Chrome's DNS prefetcher from circumventing your proxy settings, as explained in the [Chromium documentation][4].

Adjust `proxyURL` and `proxyPORT` as needed; don't forget to set `proxyURL` for both the `--proxy-server` and `--host-resolver-rules` options.


 [1]:https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
 [2]:https://unix.stackexchange.com/users/365319/dominik-matis
 [3]:https://unix.stackexchange.com/questions/534472/how-to-make-chrome-run-with-proxy-properly#comment990868_534472
 [4]:https://www.chromium.org/developers/design-documents/network-stack/socks-proxy