The EXT:copyright is overwriting fluid partials of the TYPO3 API.

Like in the illustration below the partials of the EXT:copyright will included at

Position of partial template in the typoscript tree

If you won’t have any effect in the frontend – if a copyright won’t displayed – the cause is probably, that partials of another extension will overwrite image properties.

You can check this effect, if you include the EXT:copyright with the highest element id like

lib.contentElement.partialRootPaths.21 >
lib.contentElement.partialRootPaths.9999 = EXT:copyright/Resources/Private/Partials/