Why can’t I change my email address?

Nothing is wrong. The field is read-only for everyone, and your settings are untouched.

What the field shows

Its label says it: Owner’s email, the address of the workspace owner. Unless you’re the owner, that’s their address, not yours. Your own address sits at the top of the account menu, under your name. See The account menu.

To change who the owner is, an Admin makes someone else the owner on the Members page.

Changing the address you sign in with

Jounce has no setting for it. You sign in with the address you signed up with, or with your Google account.

If you need to work from a different address, sign up with it, then have an admin invite that address into the workspace. See Invite someone to your workspace.

If you meant the address your emails come from

That’s a different setting, on the Sending page. See The address your emails come from.