Three tools for running your published app day to day, all from your workspace, none of them require unpublishing or rebuilding anything.
Viewing as a user
From the Users tab, each signed up user has a "View as" button. Selecting it signs you into your published app, in a new browser tab, as that user, without you ever seeing or resetting their password. Your own workspace tab and your own CodeBlock Studio login are never affected, only that new tab is browsing as them. When you're done, close that tab and select "End impersonation" back in your Users tab, this signs the session out cleanly so it can't be reused. Every time you view as a user, when it starts and when it ends, is recorded in an audit log for your own records, this can't be turned off, it's what makes the feature safe to use.
Feature flags
From the Flags tab, define a named flag (for example new_checkout_flow) and switch it on or off. Your published app's own client side code, or a future block built to check one, can read a flag's current value from a small read only endpoint, letting you change what your app shows or does without editing and republishing it. A flag holds nothing but a name and an on/off value, never any user data.
Maintenance mode
From the Publish tab, turning on maintenance mode shows every visitor a simple "we will be back soon" page (with a message you write) instead of your actual app, without unpublishing it, your app comes back exactly as configured the moment you turn maintenance mode back off. This is meant for short, planned windows, for example while you're making a batch of changes you don't want visitors to see mid way through.
Tip: Maintenance mode currently applies to everyone, including you, turn it off, check your changes, then turn it back on, the same way you'd review any other change to a published app.