.htaccess file produced by WordPress when you are using a permalink at the setting admin. And it changed when you try to configure those setting. So if you might want to change it manually, you must log in at your CPANEL and accessing using file manager an then customizing the .htaccess file.
Now i’d like to present a new WP Plugin that created by Lukenzi. He make WP Htaccess Editor, so you could change .htaccess in your WP Admin without log in into your CPANEL or using FTP client. The installation was easy, just download it from wordpress in here and install it into your wordpress. And then you can use the plugin already.
Unfortunately this plugin was not using an English language, so I tried to translating the plugin with Google translate help and here it is the result. You can download right here. I hope you could try this share with others.