Cisco switch logging commands

[yaredo70]

How do I check for any switch configuration changes made before and any unauthorized remote access on the switch? 

[balaji.bandi]

Depends on the switch Model - if the latest version of IOS  XE  , which logs the commands used by the user

archive
  log config
   logging enable

   notify syslog
    hidekeys

If that is not IOS XE what device is this ? what Code  the device running ?

IOS you can refer below document :

https://community.cisco.com/t5/networking-documents/how-to-configure-logging-in-cisco-ios/ta-p/3132434

[yaredo70]

WS-C2960X-24PDL, 3850, 3560 

IOS -15.0

[balaji.bandi]

above information should work for you.

[Leo Laohoo]

"sh run" and look at the top two lines and compare the timestamps of the config.text file.

Configs can be pushed via SNMP and any changes will not show up in the "sh run".