On any computers that have Semaphor already installed you'll need to take a few extra steps to remove the application data from the device. This process can be used to ‘sign out’ of an account in order to create or sign in to a new account:
Windows
Quit Semaphor if it is running. Don't just minimize the application, shut it down completely.
Open a search field in Windows. If you are running Windows 7 or earlier, this can be found on your start menu. If you are running Windows 8 or later, this can be found in the Windows start screen.
In the search field, type %LOCALAPPDATA% and hit Enter. This will open a file explorer window called "Application Data" with other folders inside. There will be a folder here named "Semaphor"; rename it to "Semaphor-YYYY-MM-DD", using today's date.
Mac
Quit Semaphor if it is running. Don't just minimize the application, shut it down completely.
Open a Finder window, then click on the Go menu at the top of the screen. While the Go menu is showing, hold down the ALT (or OPTION) key. When ALT is held down the Library folder will become visible. Click on Library, then click into the Application Support folder. There will be a folder here named "semaphor"; rename it to "semaphor-YYYY-MM-DD", using today's date.
Linux
Quit Semaphor if it is running. Don't just minimize the application, shut it down completely.
Rename the directory ~/.config/Semaphor or to "Semaphor-YYYY-MM-DD", using today's date. ~/.config is a hidden directory, so if you are using a graphical file manager you will first need to set it to display hidden files.
Final step
Restart Semaphor and follow the on-screen instructions to create a new account.
If this resolves your issue, you may delete the old application data folder that you renamed. It contains log files that we will need should the problem continue, so it would be prudent to hang on to it for a few days.
Mobile
On mobile devices, simply delete the Semaphor app then reinstall from the app store or Google Play store.