Pressure advance is in filament settings if you use OrcaSlicer, and is stored with the rest of the settings on your computer and the Bambu Cloud.
Bambu Studio did not offer any setting for PA until recently (v1.7?). Studio now stores the setting on the printer, where can be seen on the Device tab, and is lost if you restore factory settings on your printer.
Any User presets you might already have will not be available on the Device tab. Only the defaults and “Custom” filaments will be listed, and I do not see a way to just manually input a value, you’ll need to use the Studio calibration from Prepare or Preview tabs to populate the PA field.