File Open box

How can I make the Open Box’s Files of type column always be ‘All files’?

The default of whatever file type I used last is not working for me. When I need to open a file from a different directory than the one listed, I have a 50/50 chance of getting to the directory and having files listed. Sometimes the list of directories/files is blank and sometimes only some of the files are listed. I’m working in Toad 10.5.