Yes, 'shall' means MUST. USC 411 states that they shall receive and they shall redeem. However, as noted, the 'redeeming' sentence in the statute does not include 'member banks' as obligators unless the they are to be implied in the same class as a big 12 'Federal Reserve bank' as it is listed. David Merrill points out that there must be a remedy for redeeming in U.S. Notes (previously gold, silver) outside the Federal Reserve private Banksters, therefore 'Federal Reserve bank' would by law include 'member banks', UNLESS there is another law providing remedy for lawful money other than USC 411. If there is neither remedy in 411 or an otherwise law we are not aware of, then it would be repugnant to the Constitution I believe because it would be illegal to force us into a private contract in that regard.
As for the demand on your account. If you cannot change the sig card then in my opinion, you would need to open a new account with the novation on the sig card, or if they (or any bank) won't allow it, you might ask all the debtors (SS, salary) to issue checks instead of direct-deposit and then stamp the novation on the checks. This gives you control and ownership of the money and how you would like to redeem it into your account.