Everything that is on - or forms an integral part of - the PCB must be represented by a Symbol in the Schematic. You have to find or create a PCB Footprint for **everything** that is on the PCB and then find or create a Schematic Symbol for those elements and assign the relevant PCB Footprint to each Schematic Symbol in the Footprint Attribute in the right hand panel. Then when you do Update PCB... or Import Changes... everything stays put. This is explained in detail in (2.2), (2.3), (4) and (6) in (2) in the Forum topic marked [Must read]: [https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a](https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a)