I normally work with 16:9 but I have project which 4:3 would be better. How do I change the viewer and canvas to 4:3?

Thanks

dont u have to click right on the sequence( not in the timeline but in the log bin) and choose settings???

Just make sure 'Anamorphic' is unchecked in the browser.

I generally will make a new sequence (right-click/ctrl-click in the clips browser) and set that as a 4x3 sequence, then nest the 16x9 sequence in that, scaling the footage to fit the new aspect, then use keyframes and moving the clips in the canvas to Pan & Scan them to work with the new framing.

I also use this method to letter box my 4x3 footage so I can reframe my eyelines onto the top third line of the frame after the edit is done.