Where do I put SNMPv3 user in item config ???

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I am trying to replicate this :

snmpget  -v 3 -l authPriv -u foo -a SHA -A "bar" -x AES -X "foobar" -On 10.10.10.10 IF-MIB::ifHCInOctets.2

However in "Templates->Items" I cannot see how to do this.

I've selected "SNMPv3 agent" and selected "authPriv" in "security level"

But this onyl enables "Authentication Protocol" and "Privacy Protocol"

I have tried putting the username in the "Security name" field, but the SNMP checks fail with "Cannot connect to "10.10.10.10:161": Unknown user name"