Access – starting up a project

I have created a project in Access. When finished I clicked Tools->startup to create a version of my project, that will be used by potential users.

the new version created locks access to the DB tables and if I want to make changes in the way the project is programmed I cannot.

How do I unlock the locked version ?
How do I create a version that will be locked but with an option to re-open with the use of a password ?

many thanks
Itay