I dont think there are the kinds of buttons you are looking for there.
But if you want to disable systemd-resolved and/or the stub variant and/or configure the DNS then you will probably need to use the regular approach through config files.
I would probably first suggest something like this to disable the cache and set the the router as the DNS;
/etc/systemd/resolved.conf.d/zz-myconf.conf
[Resolve]
DNS=192.168.68.1
Domains=~.
DNSStubListener=no
Cache=no
Where DNS is your routers IP address.
Or maybe you just want to disable systemd-resolved altogether.
You are running a pihole and all .. so you should know how you want it to work.
PS.
If any of that is difficult then here is a command. Input your router IP in the first variable if different than 192.168.68.1 and then run;
ROUTIP=192.168.68.1; printf "[Resolve]\nDNS=$ROUTIP\nDomains=~.\nDNSStubListener=no\nCache=no\n" | sudo tee /etc/systemd/resolved.conf.d/zz-myconf.conf
PPS.
You may also need/want another option: FallbackDNS, which can similarly be added, ex;
/etc/systemd/resolved.conf.d/zz-myconf.conf
[Resolve]
DNS=192.168.68.1
FallbackDNS=192.168.68.1
Domains=~.
DNSStubListener=no
Cache=no
And could be affected through a command as well;
ROUTIP=192.168.68.1; printf "[Resolve]\nDNS=$ROUTIP\nFallbackDNS=$ROUTIP\nDomains=~.\nDNSStubListener=no\nCache=no\n" | sudo tee /etc/systemd/resolved.conf.d/zz-myconf.conf
( where again 192.168... could be replaced by any desired IP. )