Open source code exists online and many developers use the same
scripts in their applications. What aspect of a website template
application is copyrightable? Is it just the layout design and
graphics? If I use a template for selling cars, similar to others
selling cars is it as violation? I have a similar application which I
completely changed the appearances, and script to work better and
registered the licensed applications within. this website doesn't look
like like the original and i've improved on the database control.

How much change constitutes new?

I think you need to clarify your question. You used the terms "open
source".  Open source by definition is available for others to use and
to modify. That is, open source is today a technical term describing
software that si licensed to allow others to use it and modify it
freely, but prevents them from themselves copyrighting it.  If you can
verify that software is open source, then it is intended others can
take it, modify it, and use it.

An example is Linux and many applications for Linux.

However, most open source has a licensing statement available with it
that is written to make this possible, that prevents anyone from
copyrighting it. Better check this out and see if it is really open
source.

Can you provide names of the software, so researchers can look it up?