I struggle to find how to get a new location activated for later observations

I’m still unclear what you mean by

If you edited entered/edited a location for an observation when uploading it (or afterwards), that isn’t saved in iNat as a permanent place. You can create a pinned location as noted above, but these aren’t searchable by other users, though they are available to you for future uploads. See some info here:
https://forum.inaturalist.org/t/are-pinned-locations-searchable/21131
https://forum.inaturalist.org/t/can-i-save-a-frequently-used-location/14127

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