You has no idea to setup the default editor in filezilla when you view/edit page then simply use this tutorial. You want setup a default editor to your Filezilla, then follow the below steps.
Open the Filezilla
Open the edit menu -> preference from the top left corner
Open the “Filetype associations” and copy paste the code as below if you use sublime as defult editor.
If you use another editor like NetBeans, dream viewer, notepad++ then you need to find their extension and set in the “Filetype associations”. so your default files will open in that software.