X-Scale, Y-Scale, Actual X-DPI, Actual Y-DPI: Default linked, click the chain to unlink. Obviously, scaling and DPI are inversely related, but for high-quality printed output, knowing the end-product DPI is essential to avoid poor quality results. If your end-product will be a PDF for the web or for a presentation, a lower DPI may suffice. See this page at the Scribus website for more details.