You can change the Render settings in the bottom left corner of Skin Renderer.
Allows you to change the Output Resolution of the Render. Change the X and Y values to adjust the output.
Resolution Scaling allows you to quickly change the size of the Render.
Setting this value to 50% with 1920x1080 will render at 960x540, half the resolution of the original, whereas 200% will render at 3840x2160. This is useful for quickly doing Draft renders or higher-quality renders without manually figuring out dimensions.
Allows you to customise the Filetype, Compression, and where the File is saved by Default.
Allows you to change the Sampling Rate for your renders. Change the Render value under Samples to adjust this (The Preview setting should be fine at 32).
Larger values will have less image grain, however will take much longer to render. Set this to low values for Draft renders, and high values for Final renders.
To enable Denoising, go into the Render Layers tab (highlighted) and tick Denoising. This will remove some of the noise in an image, however can cause some areas to look blurry. If you're at 1000+ samples and you still have some noise, this feature is worth trying.