When I newly installed matlab2016a, I found that there was no associated m file. I found a lot of information and found that this is easier to use.
1. Download file: download address
2. Unzip
3. Add associateFiles.m in the unzipped file to the current working path
4. Double-click to open the associateFiles.m file
5. Press F5 to run to generate the MatlabFileAssocFix.reg file
6. Double click to run the reg file