This loopy bit of python will change multiple Gnome Keyring (Chrome on Linux) passwords in one go.

mass_password_reset.py

#! /usr/bin/env python

# use this script at your own risk. it works for me, but if it eats your homework and kills your dog, it's on you.

import secretstorage

# important: always run this script at least once with `mock_run_only = True` first to understand what would be changed.
mock_run_only = True

# leave empty if you only want to replace all old_passwords with new_password regardless of username
search_username = ''

# leave empty if you've set search_username and want to replace with new_password regardless of old_password
old_password = 'my_old_password'

# set to your new password
new_password = 'my_new_password'

def mass_password_reset():

    username_must_match = (search_username != '')
    password_must_match = (old_password != '')
    bus = secretstorage.dbus_init()
    collections = secretstorage.get_all_collections(bus)
    for collection in collections:
        collection_label = '%s' % collection.get_label()
        items = collection.get_all_items()
        for item in items:
            label = '%s' % item.get_label()
            username = ''
            attributes = item.get_attributes()
            if attributes and 'username_value' in attributes:
                username = '%s' % attributes['username_value']
            password = '%s' % item.get_secret()

            if (new_password != password):
                if (not password_must_match or (password_must_match and old_password == password)):
                    if (not username_must_match or (username_must_match and username != '' and search_username == username)):
                        print('found: %s, username: %s, password: %s' % (label, username, password))
                        if (not mock_run_only):
                            item.set_secret(new_password)


if __name__ == '__main__':
    mass_password_reset()