To change your display name (for personal trainers/fitness coaches), click Account in the top right portion of your screen. A drop down menu will appear. Next, click on Profile. (See image below.)
Once you are on the Profile page, click on the section next to the title Display Name. Once you change this field, it will automatically save. To ensure it saved, you can click the button Data Is Automatically Saved button. (See image below to see where Display Name is located.)
If you are a fitness coaches client and you are viewing this guide, it is almost the same exact process. Just log in to FitSW Personal Training Software and follow the same steps.