Hello Liviu!
In which .txt file are the fet software settings options saved?
That is depending on your OS.
On Linux, as nearly all applications, it saves in your home directory -> .config -> FET
On Windows, as nearly all applications, it saves in the registry
Help me, Take a screenshot of that folder for me
On Linux? The file/folder starts with a dot. If it starts with a dot, then it is hidden. You must enable "show hidden files" to see it.
On Windows? Please use regedit to see the registry. Search for FET. Don't play with the registry if you don't understand it 100%, it contains all settings of all you applications and of windows. If you do stupid stuff there, then you can disable your whole OS.
It is not a text file. It is a data base. see https://en.wikipedia.org/wiki/Windows_Registry
Thank you, Volker!
Vu Ngoc, more detailed locations are in the README file, search for "Uninstalling FET" or "Regedit".