When you move, you must report your change of address to the Swedish Tax Agency so that your address is correct in the population register. Reporting your change of address is free of charge and can be done electronically using the Tax Agency's e-service.
You should report your change of address in advance or no later than one week after you have moved. Your new address will then apply from the day you move in. If you report your change of address more than one week after you have moved, your new address will apply from the day the report was received by the Swedish Tax Agency.
This is the link to do it electronically (in Swedish only)
https://www.skatteverket.se/privat/etjansterochblanketter/allaetjanster/tjanster/flyttanmalan.4.7459477810df5bccdd480004564.html
You can log in using one of the following IDs
Official website informing how to do this including a short video in English: https://www.skatteverket.se/servicelankar/otherlanguages/inenglish/individualsandemployees/reportingachangeofaddress.4.5c1163881590be297b51920b.html