Need help: How can I re-render a picture?

Hey guys, I’m new to Blender. Today I just finished rendering a picture, then I have found some issues with it, so I went back to 3D view and made some changes. When I set up the new render settings and ready to render it again, I found that every time I click render button, Blender just swiftly render out my old picture, it was so fast that I can tell it didnt render my new picture. Can someone please help me fix this problem?

Post your blender file, it will be easier to solve this problem.

Look in the video sequencer and remove any clips there or in Render / Post Processing panel disable ‘Sequencer’