This idea has been merged into another idea. To comment or vote on this idea, please visit WEBFLOW-I-3736 Ability to override an instance ID and other style parameters of an instance.
Currently, IDs on symbols are set at the master level, and there is no way to set or change IDs for individual instances of a symbol.
There are a few ways this could be accomplished. The simplest way would be to just show the ID field for symbol instances and let us edit the ID there. Another solution would be to be able to connect overrides to the ID, like is done with text for other symbol content.