Some theme packs come with extra graphics that can be used if desired to overwrite the original 1s. Obviously make sure that you want to use these graphics before you overwrite them, and Always back up any files you overwrite 1st.

You can always make your own graphics to suit your own tastes, thus giving you more satisfaction after knowing that you made your own

If you want to know how to change those images, right click on the text image and follow the correct directory paths for each 1, and upload them to your site, hitting F5 to refresh your page to see the results.