How to modify newly installed theme for already installed packages?

[himtuna]

Hi, I have installed several packages on my site with default theme.
Now I have found a great theme, is there any easy way to modify it for already existing packages.

I have discovered that when installing a new package there is an option to install on other themes and if the test fails you can manually edit those files.
But what to do with already installed packages and newly installed theme?

[N3RVE]

Please, one support topic per support query.
Locked and marked as solved.
http://www.simplemachines.org/community/index.php?topic=296084

-[n3rve]