Change where the wings are. The location of the larger wings is typically where the CoL is, but always determines where it will be. Mirror them to have a left-to-right balance, and also: Always make sure your center of mass is in front of your center of lift or your plane won't fly.

Change the wing arangement

@Winstonlharambe oh you have fuselage blocks on top of the actual wing? Sorry but I'm not experienced in fuselage-cased wings. My few aircraft have been bare wing. Only one had fuselage blocks for wings and it was very difficult to get working.

I'll try @randomusername thanks a lot man

what if CoL is on the side @randomusername . For my model, the blue ball is slightly right, resting on the right wing

Surface or the interior structure? Cause I eliminated drag @Khanskaya

Change the wing position