The Settings panel is an accordion of five sections. Open one at a time; each saves independently.

General. Name, description and tags, with the other four section headers collapsed underneath.

Processing. The site's coordinate reference system.
General |
Site name, description and tags. Save Changes commits. |
Processing |
The coordinate system — Auto or Custom, with horizontal datum, projection, epoch and vertical datum. Every capture on the site is processed against this. |
Base Station |
Base station files uploaded for this site. Reads No base station files uploaded yet when captures used auto-base. |
qSurvey |
Which code profile this site's surveys draw their field codes from. |
qPole |
Which component library qPole builds from on this site. |

Base Station. The RINEX uploaded for this site, if any.

qPole. The active component library, with counts of what's in it.
The coordinate system locks after processing. The Processing section warns that a site's coordinate system is fixed once captures have been processed against it. Set it before the first upload if the job needs a particular projection.