Nothing for you to worry about.
The classification systems exist for two reasons. It is how the examining corp is organized. Examiners become experts in one or more related classes. Your examiner will be in an "art unit" that examines things from one or more related classes. Although you have the option to suggest a class/subclass when applying, the primary class is actually chosen by a semi-automated process based on the text of claim 1. Your application is then steered to a particular art unit. For the sophisticated, there are strategic attempts to get it to one unit vs another unit.
It is also a way to search for patents. Before there were computers allowing text searching they need to be organized in some way. We still use it in professional searching - it often finds things that a text search does not.
The IPC (international classification system) is not as fine grained as either the US or CPC and is not particularly relevant to the examining process.
In the USPTO each appliation is assigned to an art unit within a technology center. Each art unit examines a handful of closely related class/subclases. The supervising examiner (SPE) of that art unit assigns a single specific examiner to the application. The classification is based on the claimed subject matter.
If some claims would be in a quite different class/subclass from the others the examiner will issue a restriction requirement and the applicant is forced to chose which set of claims will be examined in the course of this application.