Advanced settings and high resolution textures.

Hello, this seems like a simple problem which I should have been able to figure out, but there doesn't seem to be a reference to it anywhere else. I want to run LoZ: Oot with hi-res textures in P64 1.6, but when I open the "Textures" tab under "configure graphics plugin," all I get is a message telling me that "Advanced settings are not allowed to be changed." So, I haven't been able check the option to load hi-res textures if available. Of course, I've disabled the option to hide advanced settings and looked through all the menus, but can't remove this limitation. Any suggestions as to enabling the edting of these settings would be greatly appreciated.