Part of the authorised capital can (and frequently does) remain unissued.
The authorised capital can be changed with shareholders' approval.
The part of the authorised capital which has been issued to shareholders is referred to as the issued share capital of the company.
Such an issue of shares to new shareholders may also shift the profit distribution balance, for example, if new shares are issued at face value and not at market value.
[1] The requirement for a company to have a set authorised capital was abolished in Australia in 2001, and in the United Kingdom, it was abolished under the Companies Act 2006.