the tail editor button is completely missing from the ferret business if you are using the MYM launcher to run it.
This was something I had to fix manually way back when. I think I did so by disabling "Mine Menu," but that's on my currently active mods list, and my disabled list is empty, yet I can still get the vanilla menu.
Where is it missing? Edit: you probably have to remove mod_voxelmenu_4.1.4_mc1.7.10.litemod from your mods folder so it shows up.
what sirwill said, go into your mods folder and put a .bak after the voxel menu file. re-log in and when you go into options in game it will be there at the bottom.