Hello. How was the Requirement created? The reason I ask is, Requirements can’t be created without a name. Is the name of the affected requirement displayed in the ‘Name’ column in Requirements grid? Are you the author of the Requirement you are trying to edit? If you are, you should be able to click the pencil icon next to the Requirement Name field and make the changes.
When you ask what’s the best way to file a bug, are you wanting to know the best way to create bugs or link them to other entities? Issues (Bugs) can be created in the ‘Issues’ module, or directly from a test run by clicking the ‘Fail & Issue’ button. Issues can be linked to Requirements, Tests, or other Issues in the ‘Traceability’ tab of the entity you are wanting to link the Issue (Bug) to.