Windows 10 Observations
Four minor observations from a Windows 10 user: 1. Windows 10 Start screen, press and hold or right-click the Vivaldi app; there is no option to add Vivaldi icon to 'pin to taskbar;' 2. No API Google account login to import favorites bookmark or migrate browser account settings from Chrome; 3. Import Bookmarks and Settings from Chrome browser failed, even with closure of Chrome; 4. No Startpage.com import as a custom Vivaldi browser search engine. Otherwise, the Vivaldi browser is truly epic.
1. Look strange, but I don't use use start screen. So you can try to make a link of your Vivaldi exe (even in same folder of the browser) and to add that to taskbar.
2. Vivaldi doesn't use google API. For import you should push vivaldi button > file > import bookmark and settings > and choose your chrome profile
3. Did you check in task manager if all chrome.exe istances are closed? As last choice, you can export html bookmarks from chrome and try to import in Vivaldi (this usually work). Or try to import from chrome to firefox/ie and by ie/firefox to vivaldi if you need other things as passwords/history
4. You can use search engines located in settings and set start page from there