Custom Print format for Report print

I want to add a new customize print format for existing report print format.

for example:

There is a Stock Ledger report in ERPNext stock module. I have already customize it in my custom app using hooks.py and update the js and python file. When I click on print option from this report the default print format is showing. I need to customize this print format.

How to do this?

Create a new custom report and change the format according to the scenario. Please check the example of the general ledger report.

@NCP
its not working. The report print format is showing as default format. I have tried it to Salary Register report. But it shows the same as the default format. Though js and py file is working perfectly. But html format is not changed.