Editing following for neurons
From Internet Computer Wiki
Any neuron can follow any neuron.
For neuron A (which you control) to follow neuron B, neuron A must be controlled by the NNS Frontend dapp or have the NNS frontend dapp added as a hotkey.
Navigate to neuron A in the NNS Frontend dapp.
Click edit followees
Select a topic
Once you select a topic, you can add the neuron B's neuron ID.