Dear friend,
Please check whether your FiiO Control app is the 1.2.0 version? The FW5 should be V1.26 firmware version.
Please enable the PEQ in the 'Lab Features' first. Then go to Equalizer-turn on User EQ-long press the frequency bar to enable PEQ feature.
I also took a small video for you:
Best regards
And now create any frequencies, for example: 60, 220, 1151, set any gain and Q, then turn on the music and listen, then exit the application and go back, you will hear that your preset has reset, it will also become smooth on the graph. at least that's what I have on Android. the latest firmware is 1.26, please fix this insanity.
Fiio control v3.6