Forwarding mom's mail to my address. How do I proceed?

thank you so much for all the help! I did go online and fill out the permanent change of address form. I'm now having anxiety about how to proceed with social security and medicare. My fear is that I call them to tell them of the change, I somehow won't have the information they need (am I authorized to change her address with ss, I feel like they will require all sorts of documents?) and her benefits will get messed up. Everything does directly into her bank account, from which we pay the nursing home.
Am I overthinking all this? Really scared to call social security, lol.

Change of Address is the best way to go.
You do have to notify the "important" ones that will be redirected of the address change. So any bills she gets, government mailings (social Security, IRS, and the like) should be notified of the change. The Post Office will notify senders of the change of address for 1 year but not sure I would trust that to go smoothly.
And to make it easier on you this can be done on line!

Just a change of address, sign her name if needed.

Go on line to USPS and fill out permanent change of address. I did that for my stepmom. Don't fill out the deceased address change.

Just fill out the postal card or on-line form for change of address and they will forward the mail or at least most of the mail. They even inform many of the companies of the new address. I did have to file separate, permanent, change of address forms with the banks, insurance companies, etc. The hardest ones to deal with were getting a permanent change of address for Social Security as your zip code impacts your Medicare reimbursement to the providers, and my dad's military retirement. For the first couple of weeks it's best to also check at the old address that nothing has been mis-delivered because the mailman can make mistakes. I do hold mail and temporary change of address requests for my mail frequently and it works great.

I second Goddatter's suggestions. I've done this more than a few times, and never had a problem until one Christmas.  The post office continued to forward mail, including junk, but NO Christmas cards.

I filled out a temporary change of address when my mother was in a hospital/rehab for a few weeks. Worked very well. Cancelled it when she returned to her home. It let me bring her her mail in the rehab promptly, and to pay her bills.