Over the cooktop.

Find or download the installation instructions and read them. Think about what we would need to know to advise you. Photo the hood from a distance such that its exterior characteristics are evident. Specify its make, model, intake aperture size, internal or external blower, duct requirements, etc.

Even better would be to read the extensive collection of hood threads on this forum and use them to determine what the requirements are for a hood in your application space. Then compare these requirements to the performance characteristics of your hood, which one hopes are published somewhere. You may find that the hood you have is not what you need, but we can't determine that or much of anything else without some useful information.