Hello, today I updated to Solidworks 2020 SP1.0 from Solidworks 2019 SP4.0. I am having several issues but one big issue is that when I try to open a part, it opens whatever was opened before. I have attached a video but I am not sure if it will be uploaded. So here are the steps to my issue. 

(1) Open part1, save and close. 

(2) Open part2, opens part1. -----> opens wrong part so I close. 

(3) Open part 2, opens part2

Let me know what to do. I am just thinking of going back to Solidworks 2019. 

Solution: 

This is what worked for me. Set all Solidworks files to launch with Solidworks Launcher as default. I had mine set to open with Solidworks 2021. 

Press the Windows key, type "Default Apps", choose "Choose default apps by file type" at the bottom and search for .slddrw / .sldasm / .sldprt and make Solidworks Launcher the default app.