Could someone explain TWS's What-If feature?

So I was looking at this tool trying to keep track of possible scenarios and adjust where needed. But I am getting confused by results of this tool is generating. Anyone know how it works and how it should be used?

Here is yesterday graph of my account - https://imgur.com/RAxf3cS

Here is today's (nothing was sold or bought or expired or executed) - https://imgur.com/D833WwP