Template Override

Hi,

I have changed some colours and images on a calender view so had assumed to make it permanent I could just set up a template override.

The modified files are in:

components/com_jevents/views/geraint/assets/css and
components/com_jevents/views/geraint/assets/images

so I have copied the modified files across to:

templates/my_template/html/com_jevents/views/geraint/assets/css
templates\my_template/html/com_jevents/views/geraint/assets/images

But this does not appear to work, after an upgrade the main files are over written so the modifications stop working

Thanks