Terminal.app opens different theme when launching a new shell window
Solution 1:
You have set the “On startup, open:” preference in
Preferences > General
which only selects the profile for the new window automatically created when opening Terminal with no other windows restored.
Instead, set the default profile in
Preferences > Profiles
which applies to terminal windows you create after Terminal is open.
Note that when the startup-window profile is the same as the default profile, changing the default will affect the startup-window profile as well. If you change the startup-window profile to something else it will remain as-is if you later change the default profile.