help with icon

i guys, I'm new and I want to see if you can help me. I found a WhatsApp chat template, I really liked it and I started using it, and I just put it on my website created with Wospress, I put it with a plugin. So far so good but I see that the icon that appears from the chat is not like the WhatsApp one, it is similar but it is not. So, could someone tell me where to change that icon? so I can change it and put it completely to my liking, thank you