Re-design an App

Hi All, I have an app I use for work, I have screens in front of treadmills I input the app on a computer where it displays for people 3 options for speed that got updated depends how I put them and a count down watch etc.. The app was made 5 years ago and I am having hard time to run it on different laptop because of the java updates. I want to update it to be more user-friendly and update the look. for more details, I will attach the app to see, I input the program via excel sheet (incline, speeds) and the background video I ran in the background I download from the internet. I can send you a video of how I launch it if you need to or whatever information that you need. Please Read the requirements first before you bid as I won't answer you if you don't give me details to tell me if you will be updating my current jar one or making a new one, as I hired someone who couldn't finish it and couldn't make the same app to run on a full screen just Make sure you are aware that I input large videos that are one hour long and I don't need it to be slow. One more note, I run them on Mac not windows! Good luck.