When you upload a document, you can choose in which department this document will be uploaded:
It's always possible to look at the different departments in the documents table too, in the column 'Business unit': 
A document is visible for users who are in the same business unit and have the same roles & permissions as yourself.
for example: if you are a coach in business unit A, also the other coaches in business unit A see the same document
If you want to be sure if certain documents are visible or not for particular users, then we advise testing this first with documents that not contain sensitive data.
Related articles:
What is the difference between 'save', 'share' or 'assign'?
Save, share or assign scenarios
How is the data security handled within the Panega platform?
How come I don't see some data, and other users do?
General info: user functionalities depend on the roles & permissions settings. If a certain functionality does not work within your user account, this will be because you don't have sufficient permissions for this.