I just changed to Sierra. Now my .tex files are shown as textwrangler files. How do I get them converted back to TexShop files. I can open them file/open as TexShop files but I can't double-click open as a TexShop file. I did try version 3.77 and it didn't even do this.
First do update to version 3.77. Then, in Finder, select any single .tex file and do a Get Info… (Cmd-I). Go to the 'Open with:' section and select TeXShop.app (it may have a version number next to it) and then click on the 'Change All…' button and agree to the change. From then on Double Clicking on any .tex file will open it in TeXShop even though the icon may be wrong. The problem is that TextWrangler (as well as BBEdit) defines a UTI that interferes with that defined by TeXShop.