Your understanding is basically correct, but you don't understand the actual operation.

Your funds are in a futures account, assuming that the total funds =A,

You made a deal with intermediate fund B, so the remaining fund is C,

B is called trading margin (participation in trading is frozen by the exchange).

C is available funds (free to use without participating in transactions), and b+c = a.

In the holding stage, B must remain unchanged, so the profit and loss are as follows:

Floating earnings: If B remains unchanged, floating earnings will be added to C, and when C increases, A will also increase.

Floating loss: In order to keep B unchanged, how much loss will be increased from C to B, and when C decreases, A will also decrease.

Until c is zero, or you take the initiative to close the position and end the transaction, the floating loss becomes the actual loss.

In general, before C reaches zero, futures companies and exchanges have forced you to close your position.