Windows provides an very handy "Yes To All" option
to overwrite all files without prompting for each while copying a bunch
of files from one location to another, but there exist no "No To All" option allowing copying of only the files that don’t already exist there, you will have to manually press “No” for every file to skip overwriting, However if you Hold SHIFT and click the No button it will act as "No To All" functionality and windows will not overwrite any file and won't bother you asking for each file.