Locate the active folder
The manual lists an environment-variable location, a portable_config folder beside the executable and a roaming user location. It provides Config and Open Config Folder in the context menu as a direct route. That is more reliable than assuming every installation reads the same directory.
An illustrative mismatch is a portable copy with its own folder while an old roaming configuration still exists. Editing the old file can appear to have no effect because another location is active. Record the launched executable and opened folder before investigating the option itself.
Choose the appropriate file
The manual distinguishes mpv.conf, mpvnet.conf and input.conf, with separate script and script-options folders. Identify whether the intended change concerns playback, the frontend or a key binding. Back up the relevant file before making a small edit. Keep a separate backup for each deliberately maintained copy.
Avoid importing an entire directory just to change one setting. A larger configuration can contain scripts, private paths and device-specific output assumptions. Keep each change understandable and reversible, and follow the installed release’s documentation for any syntax differences.
Verify one harmless change
Use a permitted local sample and a small documented adjustment, then record whether it takes effect. Keep the media item and active executable steady. If a command-line option overrides a file choice, preserve that launch context in the note rather than declaring the file unreadable.
For support, provide the release, portable or installed type, relevant redacted file and the route used to open the folder. Do not share a complete private configuration containing server credentials. A successful configuration test establishes that setting’s effect in that copy; it does not verify every optional script or media integration.