You should use FORMS-H, the current application form set. Keep in mind, you will need to provide information in response to all questions or sections included in FORMS-H, even if those prompts were not part of your original FORMS-G submission.
Helpfully, NIH created a High-level Summary of Form Changes in FORMS-H Application Packages that lists those elements that have changed, e.g., Data Management and Sharing Costs. If you make use of NIAID’s Sample Applications and More, keep in mind that those sample applications were submitted using earlier form sets than FORMS-H.