A password stops the wrong person opening a file; the printing and copying permissions are a separate setting. Knowing which is which decides whether you set the right one.
Two different settings both get called password protection, and they answer different questions. One decides whether a file opens at all. The other decides what a reader may do with it once it is open.
Open password versus permissions
An open password is required before the file can be read. Share it only with people who should see the contents, because anyone who has it can read everything inside.
Permissions cover actions such as printing, copying text, and changing the document. They are instructions to the reader's software. Well-behaved applications follow them; they are a policy signal rather than a guarantee, so treat them as a way to state intent rather than as a barrier.
Setting the password
- Open the Protect PDF tool and drop the document in.
- Choose whether the file should require a password to open, or only restrict what a reader may do.
- Set a password that is not the same one you use anywhere else, and write it down somewhere you will find it.
- Apply the change and keep the original until the protected copy has been opened and checked.
Check it before you send it
Close the document, reopen the protected copy, and confirm it asks for the password and behaves the way you intended. A file you cannot open yourself is a support ticket you have just created.
If you are on the other side
If a colleague sends you a document you own the rights to and the permissions are getting in the way of legitimate work, an owner password can be removed from a file you are permitted to change. The same tool that removes it exists on this site, and the responsibility to hold the rights sits with you.