New
#11
You must have tried to plug into something other than the back USB ports.
All regular USB ports (1.0., 20., 3.0, 3.1) are the same size, except for USB C, which is much smaller.
If you could share the make/model of the PC with us (or the motherboard, if it's a home built or whitebox PC), we could give more detailed help.
I'd normally suggest plugging the mouse and WiFi adapter into rear USB ports, as you'd rarely need to access the ports for them.