This is what I have done:
But still, it keeps opening 2.78!
For now I am using a Link I made that I keep in the Desktop.
Thanks guys,
JDL
Hi.
You can always edit and customize .desktop launchers with a text editor (gedit for example). I do not know if you are using official Blender or installed from repositories. Suppose you use the latest official blender 2.79 and you downloaded tar.bz2 file in “/home/YOUR_USER/official_blender” (‘official_blender’ is a folder you created). The folder after unpacking tar.bz2 file inside will be “/home/YOUR_USER/official_blender/blender-2.79-linux-glibc219-x86_64”. Within that folder you open ‘blender.desktop’ file with gedit (sudo is not needed). You can see a line there:
Exec=blender %f
You edit this line by:
Exec='/home/YOUR_USER/official_blender/blender-2.79-linux-glibc219-x86_64/blender' %f
Save changes in editor and close. Copy new ‘blender.desktop’ launcher to your Desktop.
If you leave the line “Exec=blender %f” unchanged, it will continue launching Blender version you have installed on your system from repositories if you have it so.
Edit:
Some distributions/Desktops have the possibility to configure these things in graphic mode for example from the file explorer, but I do not know Ubuntu
Yafu,
It seems these instructions are to make what’s known in Ubuntu as a “Link”, or in Windows as a “Shortcut”, aren’t they?
I guess what I really need is to find out how to edit the path used by Launcher… I started a thread for that in an Ubuntu forum.
Thanks Yafu 
Mmm, I’m pretty sure that the example I’ve given is useful for what you want to achieve. You should just find where that blender.desktop “Launcher” file is installed when you install Blender from repositories.
dpkg -S blender.desktop
That may be: /usr/share/applications/blender.desktop
In this case you need ‘sudo’ to have permissions to edit that file.
Or maybe I’m really not understanding what the problem is… But I’m really not sure how Ubuntu handles those things, with launchers and panels
Edit:
Just out of curiosity I have found this:
https://help.ubuntu.com/community/UnityLaunchersAndDesktopFiles
You are right Yafu
I was too ignorant of this stuff to have recognized your information.
Here is the same answer in lamer terms (for a rookie like me):
Open the .desktop file corresponding to the application you want to change the path for with a simple word processing app like Gedit. See command line below for location of mentioned .desktop file.
You may want to make a duplicate of this file and add “_old” to the end of its name, just in case.
Replace both “Path=” and “Exec=” lines with the new address path pointing to the application in question.
Save it.
Done.
Example command line:
gedit ~/.local/share/applications/blender.desktop &
A more elaborate answer:
Thank you again Yafu