LTSpice has a "save the plot window" function.
To save a simple circuit simulation and its associated plot, I just maximize the LTSpice window on the screen. I keep adding traces and/or multiple plot panes to show the relevant outputs of the circuit. I then hit "Control Print Screen" Windows function. That copies the screen dump to the clipboard. I then open IrfanView, and do a Paste. I stretch a box around just the plot pane and circuit, and then Save As a JPG. The JPG is what I upload to the forum...
Look at this from a previous post: