I'm looking for a process to replace the status quo of notepad and Excel. We've tested a market-leading password manager. An issue that comes up with this is that the secure sharing password facility has some significant vulnerabilities. We want to allow a Manager to share access to her account with her PA (e.g.) without the PA being able to view the password or change it. The password manager offers this facility with password injection and shared folders within the app, but it has 2 big shortcomings:
The PA cannot directly see the password in the password manager, but she can inject the password into a website (e.g. LinkedIn), then click on the view icon next to the password field and see the plaintext.
Some websites offer a change password facility. The PA can inject the password in the "old password" field, then type whatever new password and confirmation she wants. To make matters worse, the PA has read-only on the password manager shared folder, so they lose the ability to write the password back.
Are there any options that allow account access to be shared, but do not reveal the password under any circumstances?
I suspect they all have the flaws above due to the way browsers, apps and web pages work, however it would be good to know if the above is technically possible to achieve.