User settings are usually found in ${HOME}/.ssh/config and can be created by any text editor. Each setting can be specific to all hosts, a group of hosts or individial hosts:
Set Escape Character
If you use a serial connection via a ssh session, there is a clash because most serial sessions (IPMI SOL) use also ~. as a method to end a (serial) session. This will remap the escape character to CTRL+Q for all hosts: