First, let's clarify the terminology. "Global Mapper 210" generally refers to version 21.0 of the software (released circa 2018-2019). The "Portable" designation means the software has been configured to run directly from a USB flash drive, external SSD, or cloud-synced folder without a traditional installation into the Windows Registry.
Save entire map state: File > Save Workspace → save as .gmw (e.g., D:\MyProject.gmw ) global mapper 210 portable
Tools > Configuration > ProjectionView > Projection > Use Custom Projection