Help with uploading

Hello,

This is my first time attempting to Marlin for my 3D printer, I have gone through the troubleshooting guide and have no idea where to go from here. I made all my changes in arduino, uploaded the file, but none of my changes have took effect on my printer. I am using a longer lk4 pro printer, has an atmega2650. Any advice or suggestions would be great, sorry for the non specificity of this post, I am not very experienced in editing and uploading firmware.

Did it get uploaded successfully ? what sort of changes between the previous and current versions ?