If you are using a mobile device, the default keyboard does not always play well with the freeCodeCamp editor. I recommend you read the article on using a mobile device to view some tips - most importantly, check out the coding keyboards listed as they interface with the editor well.
I think it might be browser incompatibility. It looks like you are using a very old browser. I would suggest you use whatever browser you are able to update the most and make sure it is updated as much as possible.