How to be able to change the password to access data encrypted with AES-GCM, without reencrypting?
This is case for the Fundamental theorem of software engineering which states:

&quot;We can solve any problem by introducing an extra level of indirection.&quot;

In this case what is usually done is introducing an extra randomly drawn intermediate key (usually called &quot;data encryption key, DEK&quot;).
You then encrypt the DEK with a key derived from your password (also sometimes called &quot;key encryption key, KEK&quot;) and whenever you want to change the password you simply rederive the KEK, decrypt the DEK and derive the KEK under the new password to encrypt the DEK with (also preferably using a fresh salt).