The TPS files are the data files that the program uses to store the information that you enter into the tool. They need to be in the same directory as the Fish Tracker program file, or the tool will create new ones (which will be "blank." There isn't a "save" function; the program automatically saves the data that you enter into it.

You might want to double-check that you are always running the Fish Tracker from the same location, so that the data that you enter is always saved in the right place.