See "How do I edit my research item's details?" in https://help.researchgate.net/hc/en-us/articles/14293081125777-Reviewing-editing-and-featuring-your-research for instructions.

When you had to change it in your uploaded paper, you go to your profile, click the paper. There is a blue button "share". And beside that button there is a dropdown menue "More". Click "add file" and upload the newer version.

When you want to change the description: Also click on that dropdown menue and click "Edit". Now you can change the title or description. But this affects only the title here on RG and not in your paper.