Can't change the screen resolution when using a QHD (Quad HD) and Full High Definition (FHD) monitor while it's connected to the same docking with a display set to extended mode.
To change the screen's resolution, go through the following steps:
A docking station or port replicator provides a simplified way of connecting multiple peripherals like keyboard, mouse, printer, external hard drives and one or more external monitors to a laptop PC which usually have limited connectivity ports. Most docking stations or port replicators have video ports to connect two or more external monitors and is similar to connecting your computer to your monitor, you just need to have the correct cables.