I think you may be confused about something.

Open an existing project. Change the colors. Save the project. Make the album. Preview the result (refresh your browser cache). If it looks right, upload it. If you later reopen that project, it will show the new color scheme.

When you save the settings as the default, that doesn't change any existing projects. The new defaults apply only to a newly-created project. If you open an existing project, it doesn't change to the new defaults. It retains whatever settings were there the last time it was saved.

There is one twist. If you open an existing project that still have the old colors, but then choose the same skin again, it will apply the new default settings to this project. But be careful - that will also wipe out any other project-specific settings. Everything will be reset, as if this were an entirely new project.