Add a toggle in the Welcome screen (enabled by default) to persist the configuration for this session
When you have enabled persisting the Welcome Screen settings then Tails will always persist them.
But you may only need one special setting for this session so at the next boot you need to remember to revert this setting or Tails will start with it again because it is persisted now.
When you realized your mistake you may need to reboot Tails and in the worst case you already connected to a network you really didn't wanted to connect.
A toggle that let you decide to not persist the configuration this time could help.
Persist configuration toggle could be located close to the password field of the persistent storage,
invisible when there is no persistent storage,
greyed out when the user decided to not persist the Welcome Screen settings or when the persistent storage is locked,
enabled when the user has persisted Welcome Screen settings enabled and persistent storage unlocked.
So when you don't want to persist your settings for this session you could click the toggle and Tails would not persist your settings this time.