If you're clicking the "Save changes" button and it seems like your draft isn't saving, it could be due to a couple causes.
The most likely problem is that you're having connectivity issues. Be sure to check your internet to make sure that you haven't lost connection, and save frequently as you create your story to make sure that in the event you do lose connection, you haven't lost your entire draft.
Otherwise, if your internet connection isn't the cause, it could be because your draft is particularly long, or has a large amount of embedded media, or for some other reason has content that just isn't agreeing with the editor. No worries—just reach out to us here and we'll take a look.