It is stated in the Instrument of Government - one of Sweden's fundamental laws - that the Government "governs the Realm". But if the Government is not accepted by the Riksdag, it may be forced to resign.
The Government can resign for various reasons. One such reason is that support for the Government changes after a parliamentary election.
In Sweden the Speaker of the Riksdag has a central role when a new government is formed. It is the task of the Speaker to propose a new Prime Minister as soon as possible who can appoint the other government ministers.
The Government may be reshuffled considerably without it being a question of forming a new government. The Prime Minister may replace ministers, transfer ministers and increase or decrease the number of ministers without consulting the Riksdag.