If you need to tie a Document to a particular account for a contact, there are two ways to do so.
To illustrate, let's take a look at the Accounts page for Tony Stark:
Now, let's say that we want to attach a Document to one of these Accounts.
The first method would simply be to upload a document into Tony's CRM Document Storage area. Then, from Tony's Documents page, you would select "Linked Accounts" from the Document's Actions menu:
You'd then receive a modal where you can click inside the Account box to select from any of Tony's accounts in your database to tie the Document to:
After making your selection and clicking "add account", you'd then see the account displayed, confirming that you've linked it to the document:
Click "add" again to select additional accounts to link the document to (or the red x next to one that is already linked to unlink it).
After making your selections, if you then go to the Account's Details page and scroll to the "Other" section, you'll see that there is a Document linked (or multiple Documents if you've linked more than one) and can click the number to see and download those documents if necessary:
The second method to link a Document to an Account is to add it from the Documents section on an Account's Details page. So, if we clicked on the "1" in the highlighted area above, we'd then see the below:
First, note that you see the previous Document linked to the Account. To add another one, click Upload and you'll be able to add a file or files for upload. Once uploaded, the Documents will be linked to the Account (and stored in CRM Document Storage).
Regardless of which of these methods you use, the linked Document(s) will then be on display within the Account Documents section of the Account Details page for that account, as displayed above.
Also, Documents linked to Accounts will display on the Contact's main Documents page, just like other Documents, but with an Account Number in the Account column.