try to understand ground and power planes
The basic rules are very simple. The consequences of those rules can be quite complicated.

A DC current will flow in the path of least resistance. 

An AC current will flow in the path of least impedance.

For DC, the path of least resistance means that current will spread out and cross most of the ground plane, between the IC connection and the power supply connection. This may or may not be what you want, if the current flows through parts of the ground plane that have uV sensing across them. This is where careful placement on the plane, and even cutting slots in the plane can be required to control where current flows.

For very high frequency, loop area is so important that where there is a signal trace above ground, the signal current will flow on the underneath of the trace, and the return current will flow on top of the ground plane below the trace. 

At lower frequencies, resistance plays a bigger part in impedance, and the situation is somewhere between the DC case and the AC case.

Ground planes are a mixed blessing. If you're lucky, they avoid the need to think about return current paths. If you're unlucky, they can get you into all sorts of trouble, because you haven't thought about return current paths.