can you edit existing software?

I agree, its difficult.
Software mostly has API which are customizable for clients modification.

Hey Mark, as others have pointed out, it all depends on several factors. All software CAN be modified, if you have or hold rights to the source. Some software is easier to modify than others.

If you are referring to server based software (CGI, PHP, ASP, etc), then it is easy as h*ll to modify, especially if it's not encrypted and the license allows for modifications.

Also note that most unencrypted script owners do not mind you modifying the script to suit your needs, however, (a) you are not allowed to resell it as your own and (b) your changes will be unsupported. IOW (in other words) if you screw something up, the script writer will no longer offer support as s/he has no idea what changes you made and how well you can code.

If, on the other hand, it is a compiled application, such as a windows based EXE file, then it is a lot more difficult, but still very possible, if, again, you have the source code.

As a software developer in many different programming languages, I can tell you with almost 100% certainty, that if it is a compiled app, you will be hard pressed in obtaining any such rights, unless, the app was created with the intent of selling PLR (Private Label Rights) or source code access with it.

When I create compiled applications (exe based software), no one, and I mean no one, will ever have access to the source code other than myself and my partner should I decide to use one for that particular application.

However, most software developers are usually more than happy to offer customized versions, but usually at a cost. Sometimes, it may often be beneficial to use sites like freelancer.com or odesk.com to hire a programmer and have a software app created from the ground up to do exactly what you want or need it to do to meet your own needs.

I will soon be launching a site called Software Creation Labs and many articles will be posted that relate directly to the question you just had. If you'd like me to notify you once I launch the site, please feel free to PM me and let me know. I will add you to my "notify on launch" list.

This is not an actual autoresponder based list, just a simple list of email addresses I keep in a notepad file of people asking me to let them know when I launch the site.

If you have any more questions or would like to discuss my post further, please feel free to post below or shoot me a PM. I could talk software all day long

HTH