You have to know the path to the Dev version in order to run from it from the run box.

Open your computers file browser to the Programs Folder(s). Windows: C:\Program Files and C:\Program Files (x86)

Look for any Mozilla Firefox folders. Look inside and right-click on firefox.exe Select Create Shortcut. Place the shortcut on the desktop and rename it using a unique name so that other shortcuts can also be placed. (Version number, how its used . . . .) Example (on my system): Firefox_54 Firefox_Current

Repeat the above for each Firefox.

Note: Different versions of the browser can not share the same profile so each should use its own profile.

Thank you two, your solution inspired me. I checked the environment variables and Firefox wasn't there, so I went to the Registry and found something.

Turns out, windows has a registry to store the location of applications, which is located at HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths These registries allow you to access applications in "run" without setting environment variables.

So here's my solutions:

1. Edit the registry located at HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\firefox.exe
2. Create shortcuts for the two browsers and name them firefox and firefoxDev
3. Put two shortcuts into C:/shortcuts/
4. Add C:/shortcuts/ to PATH

That was very good work. Well Done.