Try create new topology; if you cannot configure anything on your own topology, then re-install PT. PT 7.3.0 is the latest. there are some bugs with PT on MACs OS. you may want to switch to Windows till bugs are fixed.
Config term gets u into config mode; type exit to exit back to user mode and you should see system log "Configured from console by console"
if you have disabled Console logging, you should not see such message; PT is a sim with few bugs (or some commands do not exist or not working properly). Mostly PT is great tool to learn Cisco at CCNA level.
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