Can anyone tell me how to navigate to a itemized monthly invoice
Do you need the actual invoices for each order or just pertinent info from each?
If you're having to prepare something like a monthly report, in the Orders section mentioned above, you can limit your search to the last 30 days. There are 4 categories at the top: Orders, Open Orders, Digital Orders, & Cancelled Orders, so each one would have to be opened to get the info from that category & you'd have to pull it together manually.
This one can be a bit difficult to maneuver:
Sign in, go to Your Account, & down the left tap Download Order Reports. When you get there, there are variables you can fill in - specific beginning & ending dates, periods, etc - & download the reports. Depending on which app you use to open the downloads, you can end up with a huge jumbled mess of info or a nice but very wide report with column headings & probably much more detail than you need, but it's all there.
And just for completeness' sake: This is a forum for getting help with Amazon's digital devices and services not general customer support. You should contact Amazon directly for questions concerning your account.
Based on past posts, similar in nature, very possible OP thinks they're contacting Amazon about their credit card statement (under the assumption it was generated by Amazon because they have one of the Amazon-branded credit cards) and wanting detail on all the various Amazon line entries. If such the case, they should be contacting the bank associated with the card.