Need to change text for titles "Chat with us" and "Call Us"

[Kamran Rai]

Hi,
How can we change the titles "Chat with us" and "Call Us" when chat widget appears on our site?
I am using it on my personal site, so I want to refer to "Chat with Me" and "Call Me" rather than referring to as an agency.
I can't find any option in dashboard.
How do I do it, tried changing the "callus.js" file but than widget doesn't appear at all!