Hi Pruthvi. I know the method, it must work for 6.2.0, and not checked for 6.0.1. (Be ready for making revert) You should export Current theme, and make updates for Colors or Styles in templates. Then you import the Theme back, and new colorsstyles will appear. Step1. Export Themes and unzip archive export.zip.
Step 2. Find the files *.jrxml.data and update styles as you like. Move files back to archive export.zip. Step 3. Import export.zip and check how it looks now. Picture for step 2: