My check was mailed out, but my PO BOX is closedown. What should I do?

Can you have your mail forwarded to a new address with the postal service?

I did that, my check was mailed 3/5 are 3/6 hoping that it gets forward me & not back to the IRS. They say it can take up to 7 days to have it updated in the system as forward

You can try to call the IRS's toll-free number at 800-829-1040,  M - F, 7 a.m. - 7 p.m.