IRS tax withholding estimator

I’ve been OE for a little over 2 years now. Every beginning of the year I get fkd with taxes. All J’s are W2.

I keep meaning (but forget) to use the IRS tax withholding estimator to determine the amount I need to withhold at each job to not have to pay minimal taxes.

I just took on a J3 and need to do this asap. My question is, I know it tells you to checkmark that box on your W2 stating you have another job etc. is there a way around that? Wouldn’t each J see you check marked that box on your W2 and raise questions?