I have 4-5 active pipelines for different purposes. How do I designate one of them as my default pipeline, so that 'deals' always opens in this pipeline?
There might be a setting for this. I am not sure at this time as all my deals are created by APIs.
For me the deal is always created on the pipeline that is currently active on the user browsing.
If you want to enforce new deals to be created on an specific Pipeline you can always create an automation with trigger being created deal and action being change stage to the stage you want. That will enforce your default.
Hope it helps and as always I am available for hire for all things Pipedrive.