Why this move matters
Overspending is not a failure, it is a question waiting for an answer. Notice is where you found it. Direct is where you settle it: you decide what gives, and you say so. Leave it unanswered and one category sits in the red while the rest of the plan carries on as if nothing happened, which makes every number after it wrong. Covering takes seconds, and it is what keeps the plan worth reading.
Do it in Vondo
1. Find the category that went red. Notice left Groceries overspent. On the Budget screen its Available amount is red, and it is not only a number, it is a button.

2. Open it. Cover Overspending already knows which category you are fixing and how far short it is. You do not type an amount, Vondo works it out.

3. Choose where the money comes from, under Take money from. There are two sources, and the difference is worth understanding.
Unassigned is money you have not given a purpose yet. Covering from here spends money that was still waiting, so the rest of your plan is untouched. Vondo only offers this when Unassigned is actually holding something. If you finished Organize by bringing it to zero, this option will not appear at all, which is right rather than broken: there is nothing sitting there to spend.
Another category trades one plan for another. Dining out loses exactly what Groceries gains, so your total assigned does not change at all. Only categories that really have money left are offered, so you cannot quietly drain an empty one.
Either way Vondo shows Will transfer with the exact figure. If the source cannot cover all of it, it tells you how much still needs covering from another source, so you can take part from one place and the rest from another.
4. Confirm. Groceries stops being red, the source drops by what you moved, and the red is gone from your budget.

5. Use it before something breaks, too. Direct is not only a repair. Any category with money left offers Move money from its row, where you pick a To category and enter an amount, capped at what the source actually has. That is how you handle a plan that changed rather than a plan that broke: the car needs a repair this month and the trip can wait, so you move the money and both categories stay true.

What you should see now
Nothing red on the Budget screen. Every category reads green or grey, the money that covered the overspend came from a source you chose deliberately, and the plan still adds up. You did not break the budget and you did not look away from it. You steered it.
You just did the D in VONDO
Next comes Outlast, where you stop reacting to the month and start arriving ahead of it.
Power tier: covering the same category every month is a sign it needs a target rather than a rescue, see Targets and Quick-fill. Overspent on a credit card? Only the part you had already assigned moves across to the card’s payment category. The rest is a charge you have not funded, so it becomes debt on that card until you cover the category here, and the coverage follows once you do. See Credit cards.