I am setting up a new Gmail and want every email sent to the old one to arrive in the new one. How do I set up forwarding?

In the old account:

1. Open Gmail on a computer and click the gear > See all settings.
2. Open the Forwarding and POP/IMAP tab.
3. Click Add a forwarding address and enter the new address.
4. Gmail sends a confirmation to the new address. Open it and click the link.
5. Back in settings choose Forward a copy of incoming mail to, select the new address and choose what to do with the original (keep it in the inbox is the safe choice).
6. Save changes.

Forwarding is for new mail only. Old mail has to be moved separately, for example by adding the old account in an email app by IMAP and dragging folders over. To forward only some messages, create a filter instead (Filters and Blocked Addresses tab).

Forwarding works. Will do the old mail in Thunderbird. Thanks.