Mouse buttons swapped but not showing a diffrence

I was in champ select and my mouse was still being fine like MB1 was to select things but MB2 of course wasnt needed to be used. but till I got into game all the sudden my MB1 is my movement and attacking and my MB2 is my buying and pinging button. its irritating me so bad anyone know whats wrong? I tried changing the primary to the mouse to Left and still doesnt fix.

I plugged my cousins mouse in and all the sudden I was able to move and attack with MB2. I could use his but he needs the mouse and I just wanna fix my mouse.

Thank You.