Writing on the whiteboard

When I use the writing tool on the whiteboard the letters have borders so it's very difficul to read. This thing happens on one of our zoom accounts. I tried to change the format, but I can't find the option for this, I can change to bold, italics or the size, but that's all. What;s interesting is that when I'm typing the letters mook normal, after I've done and click on the whiteboard they get this weird shape with orders and shadows. Any advice will be appreciated.