Why is WiFi signal strength low on my INSPIRON 15 5559?

Okay so I recently bought this laptop everything is perfect except wifi signal is extremely low even when I am next to router it only receives maximum of 2 bars on windows 10. When I purchased this laptop from my local store I told them to swap 8 gigs of memory instead of 4, so i'm thinking maybe while they made the swap the wifi adapter got loose or something? Can anyone help me on what I should do? Its really frustrating to use WiFi on low signal! :(

p.s: should I try to un-mount and mount the card again?