Unfortunately, there's no way to transfer canvas data stored in the cloud to another pixiv account.
Please link a different pixiv account through the app and sync your data to the cloud from there.
To switch accounts, please log out of the current pixiv account in the app and log in with the pixiv account you want to use.
If your canvases do not sync to the cloud automatically, try duplicating them in the app. The new canvases will sync to the cloud.
(The canvas version history will not be duplicated.)