@Drachenfire76,
Both of these settings are more advanced configuration options meant to either be used with specific features, or for troubleshooting connections. IGMP is mainly used for managing IP addresses of IPv4 networks, but some services, such as Apple's HomeKit may be able to operate better with the feature enabled. With IPv6, this is far less important, especially on newer routers. I would recommend leaving the setting as is unless you are having difficulty with some services.
The WAN Unicast feature is meant for networks that are having difficulty receiving the IP address from their ISP. Some ISPs are not compatible with this setting, so it is also not recommended to enable this setting unless your network cannot receive an IP address from your ISP.