itch.io

Steam: should update automatically if not just click on the arrow and it should say "update" 

Mobile: go to the play store or app store and search the app and press "update"

If none of these worked then uninstall then reinstall it :) 

- Hope this helped

it's available on steam you can still get it for the same price as itch.io

If you guys are having trouble updating the app either redownload or click on the arrow and update I don't know how else to help I didn't have a problem (or you don't have enough space).