Output the mask
With a good mask made, an extra step which will often help is to tick the Decontaminate Colors box under Output Settings. You can assess the results with and without this to see whether it improves the effect. Once you’re satisfied, select the New Layer With Layer Mask option in the Output to: dropdown box, then click OK. If needed, you can now further refine your mask by painting black or white into it with the Brush tool. With a good cutout in place, you can now easily change the background simply by dragging a new background pic directly into the image, and placing its layer above the current background.