The refund amount changing could mean that the IRS or your state adjusted your return based on information that they had that is different than what you reported. Generally, the state or the IRS will send a letter notifying you of the changes.
Other missing dollar amounts may be caused by a refund offset. This is when the government applies part or all of a taxpayer's refund towards the taxpayer's past-due income tax, child or spousal support, student loans, or state unemployment compensation debts.
Please click Why is my direct-deposited refund or check lower than the amount in TurboTax? to learn more.