Select by backups : If you select this option  , the tree view will list all databases that have been backed up .  You just select a database in the tree view you want to restore , it will list all backups of the database in the list view.   
Select by jobs : If you select this option , the tree view will list all databases selected in backup jobs. (These databases maybe have not been backed up in this case) . This option is  helpful if you plan to "Synchronize" two database via backups, that is backing up a database and restoring backups to another server. 
Always select the latest backups automatically : Select the latest backups for a valid restore operation automatically. If the database has not been backed up , you can define a restore job using this options .
Select following backup by myself : If you plan to restore database using some specified backups , please select this option.

Recommend : By clicking this button , the program will select the latest backup in list view to restore database. This option is recommended if you want to restore database to latest status or do not know which backup to be selected.
Clear : Clear all selection.
Select one by one : If this option is NOT selected , program will select backups needed to restore a database automatically . If this option is selected , you should have a deep knowledge of MS SQL Server administration , you can select backups freely in a restore job or restore database step by step in several jobs.