Square outside the stereo does not read the U disk how

1, sometimes it is not searchable, do not use too many layers of directories.

2, the file format is not supported.

3, the system does not support the U disk, that is, there is a problem with the compatibility of the two in hardware or software.

Suggestions:

1, first, reformat the USB flash drive once.

2, the song is confirmed to be mp3 format.

3, Try the song in the root directory.

4, if it does not work, try another USB flash drive.