Firefox: Your browser is managed by your organisation

[Guest FreeDee]

In Firefox i tried to check the Checkbox "General -> Startup -> Open previous windows and tabs" but the checkbox is'nt free.

Above the Checkbox is a text "Your browser is managed by your Organisation"

Google search gives hints to generally internet-Security-suites. Few weeks ago I changed from kaspersky to ESET.

How can I fix this?

[Marcos 4,935]

ESET's sets only security.enterprise_roots.enabled, other settings are manageable by the user or organization. Installing ESET should not affect the above mentioned issue. Is it really Firefox and not Chrome or Edge that is displaying the message?