This Bug Report is also directly related to this Feature Request: [https://easyeda.com/forum/topic/Please-reinstate-the-DETACH-function-8b6fe2d37d6c4f8f8a4071055c3879af](https://easyeda.com/forum/topic/Please-reinstate-the-DETACH-function-8b6fe2d37d6c4f8f8a4071055c3879af)<br> <br> Some months ago I successfully created a spice symbol for the V2164 quad VCA as a 5 sub-part symbol:  I have successfully used this symbol both for simulation and non-simulation schematics for 2 differnt designs and from which I have produced PCB designs with no issues. (Please note that Ihere are also other non-spice symbols for the V2164 but they not the one's that I am talking about here.) As noted in the Feature Request above, if I select, cut and paste a sub part, although the sub-part number stays the same, the main device prefix number is changed to a new number. * I then find that for the V2164 spice symbol I cannot change the main device prefix number of the sub part back to what it was originally. * I think this behaviour has changed within the last version or maybe two versions of EasyEDA because I have previously been able to edit their prefixes. There is no warning that the part already exists: the number just does not change. Saving and refreshing does not correct this problem. Cut or copy and pasting the sub part again does not correct this problem. Deleting and then replacing the sub-part from the library does not correct this problem. The only way I have found to correct the problem is to edit the main device prefix number in the JSON File Source for the schematic.