Unfortunately it's not possible to restrict filters to specific reports. You have 1 default filter per report (which is configured when you build the report) which is specific to that report, any filters you create outside of the report builder are available for use on any view in the system by any user that you share it with.
The best way to provide additional filtering capability that is restricted to a specific report would be to use prompts to allow report users to choose the filter criteria they want to apply to the report. You can either build a standard prompt and let users pick their own filter criteria against the fields you surface within the prompt, or you can build custom prompts and predefine the filter criteria that is available to them. Take a look at this article here on Workfront One for more information about prompts.
I hope that makes sense, however please shout if you have any questions and I will do my best to help!