Time zone settings

If we have processed in one Timezone on a project (eg UTC) and then Edit Project Settings to change timezone to another, ie UTC+1, does all new data being processed now get the new Timezone applied?

>>New timezone will only apply new custodian. Project setting timezone is used as default when new custodian are created.

And if so why does existing custodians still show the older UTC timezone, and will any new data in an existing custodian be processed with the UTC or UTC+1 ?

>>As mentioned above, ingestion will use the custodian's timezone setting. Hence it will use UTC. If you want to process  just few new medias on different timezone than current data  in a custodian, you can ingest those media in new custodian with correct timezone. Once processing completes, use the 'merge' custodian option to merge those two custodian together.