Help Google Photos Back up Quality

[Android Question]

Hi,
I have lots of photos backed up using Google Photos auto backup at standard quality.
I wish to upgrade the back ups to full quality, but the setting only seems to apply to photos going forward. How can I make my phone re-backup my photos using Full quality please?

 

[Mikestony]

Not sure, so this is a shot in the dark......download your photos from google photos to your computer, wipe the photos from google, then re-upload them?