Fiio in new firmware versions corrects errors, makes useful changes, improves the stability of the device, but if you were completely satisfied with the work on the old firmware version and you want to return the VU-Meter visualization, then you can try rolling back to the old firmware.
No, resetting to factory settings will not return the old firmware version.
I don’t know) Last night I read the instructions for rolling back the firmware in my native language, but, to tell the truth, I couldn’t figure it out, since this requires experience in practice, but I no longer have X5-3 for me it’s difficult to translate the sequence of actions for you to roll back the firmware. It's not so easy. I do not want to give erroneous advice and thus turn your music device into a brick. I advise you to write to the discussion thread on the X5-3 forum and ask for advice, I think there will be people who have experience in rolling back firmware.
https://www.head-fi.org/threads/fii...d-dts-android-dual-card-slot.828402/page-1040
Information in Russian:
https://4pda.ru/forum/index.php?showtopic=825351&view=findpost&p=73841818