Before running `gdbgui`, you should compile your program with debug symbols and a lower level of optimization, so code isn't optimized out before runtime. To include debug symbols with `gcc` use `-ggdb`, with `rustc` use `-g`. To disable most optimizations in `gcc` use the `-O0` flag, with `rustc` use `-O`.
For more details, consult your compiler's documentation or a search engine.
Now that you have `gdbgui` installed and your program compiled with debug symbols, all you need to do is run
`gdbgui` settings can be accessed by clicking the gear icon in the top right of the frontend. Most of these settings persist between sessions for a given url and port.