The rhythm of the tests and which eye is tested is set by the application's algorithm. Each day, when you open the OdySight app, a new visual test will be required. If one of your tests is locked, it means that you did not do your required test yet.
In order to unlock the tests:
Open your app and use your password.
Once in the app, click the eye at the bottom right corner of the screen to display the list of tests.
Start the required test, displayed in red.
Click on the exclamation mark to show the list of tests
Click on the test with an exclamation mark to start your visual test of the day
Once the required test is done, the other tests will be unlocked and you should be able to launch them.