Did you search through the Makefile? I’m not using Workbench often, but I thing it’s the same as when compiling without Workbench. Try to find parameter -o in the Makefile.t3m or how the makefile is called.
Did you change the name of the Project file itself? When I compile a game in Workbench, the interpreter window shows my new name, but the t3 file in the debug directory is still named after the project file.
By golly, you’re right. At a guess, there’s no Save Project As… command in the File menu because it would be non-trivial. The user would have to decide whether to copy the source files to a new directory or use the existing source files. All sorts of file pointers, etc.
But it’s not difficult, really. Just create a new project but (if you prefer to do so) put it in the same directory as the old project – that is, create NewProject.t3m, but put it in the OldProject folder. Then delete NewProject.t from the Source files and add all of your existing source files by right-clicking on the Source Files folder in the Project Browser. (You’ll have to drag new files down below the library files.)
When I do this, the new _dbg.t3 file doesn’t seem to go into the debug folder; it seems to get parked int the main folder. Not sure why.
A better solution, then, is to put NewProject in its own folder while creating it, manually copy the source files into that folder, and then add them to the project.
It’s in the Build Settings. Click on the Build menu -> Settings, then Output in the list on the left. You’ll probably want to change all three of the file names here, but the one for the debug build is the first one.