Configuration audit syslog messages

Yes, Audit logs is by default enabled on BIGIP but if you make the changes through tmsh or webgui then you will see the logs in respective directory only like you make the changes through TMSH and you cannot find those audit logs in webgui and vice versa.

Audit logs will give you some clarity like time and date,username and password and trasn id in the logs.BIGIP store locally last 8 days audit logs.