I have finished my schematic for an echo circuit using PT2399 IC as per the application circuit in datasheet. I have downloaded the part (including footprint) from snapeda.com and updated my Altium library. But I can't update the design to PCB. There's no option as 'Update PCB document' under the 'Design' tab to update the design to PCB. But it is showing for other projects I have done. I don't understand. Please help me, it's urgent.
Altium Designer is similar to, for example, Microsoft Visual Studio and other major development applications, in the sense that you can open a single document or an entire project (collection of related documents).
When you have just a PCB or schematic document open, Altium has no context for updating one from the other. If you have the project open — even if you only have one schematic within it actually open — then Altium 'knows' which PCB you want to update.
The file extensions of interest (per Altium 19) are:
PrjPcb= The entire project
(It may help to have file extensions shown.)