Good Morning, 
I’m looking to find the solution for a very basic question (I suppose); I’ve already watched ±10 hours of Sketchup tutorials online but still can’t find how to do this simple thing :
When I draw a rectangle for example, how can I change the length of one side only ? When I choose the tape measure tool and click on the two points of the side I want to change and then enter the value I want (at the bottom of the screen), I’ve automatically got a pop-up opening saying “do you want to resize the model ?” and if I click ‘no’ nothing happens, if I click ‘yes’ it resize the entire thing keeping the proportions … (and basically I just want to change the length of one side only, then I won’t have a rectangle anymore btw …).
Same thing when I’ve got a rectangle that I draw on a pre-existing plan, it will resize the rectangle + the plan underneath (and again what I would like is to change one side only of my rectangle, just that simple … 
).
I know it looks quite simple but I can’t find how to do that simple stuff even after many tutorials watched and google researches, but maybe that’s just me who’s completely dumb or I’m just missing something here … ? lol (I used to work a lot with a software called ‘Solidworks’ a few years ago, so maybe I’ve got a false approach here, even if Sketchup looks more simple to use).
Thank you per advance for your help, that would be really appreciated !
Rusty From France.