Kerbal Space Program

Hi, I am having issues with the staging in the Assembly building with staging when trying to move different components about on the staging list they won't go into the boxes whether it's a new one I have created or it's an existing one, this also seems to be the same even if I try to edit the staging while on the launch pad or in flight I am fairly new to the game but feel this is something with the game rather than it being related to my actions

thank you for taking the time to read my message