[Question 1]
Please tell me all the necessary settings for zabbix to receive traps with SNMPv3.

On the host screen of settings, register the host, select SNMPv3, and select the security level.
What should I set for the context name and security name?

When creating the item, select Name, Type: SNMP Trap, Key: snmptrap.fallback, and Data Type: Log.

Are any other settings required?

[Question 2]
Please tell me how to change the following password.
・MySQL Zabbix account
・MySQL privileged account