Editing lyrics

I'd like to edit the lyrics that are inside the .MP3 and .FLAC files I have.

I use the Foobar2000 player and this player allow me to choose if I want to get the lyrics from the Internet. But if the files already have lyrics inside, the player doesn't search a new (and, hope, better) lyric, brought from the Internet.

As i took a look at MP3Tag, I've found UNSYNCEDLYRICS field in some files. And the files which have this fields, the player always show it contents as lyrics. But it's not rare this field are filled with advertisiment. And when I try to delete these contents, the window i access through ALT-T doesn't keep the "OK" button able.

Actualy, if it's not ask too much, using MP3Tag, I'd like to split the columns panel horizontally: the upper side keep the columns, the down shows me the lirics. Is it possible to do this customization? Or, alternativelly, just delete the fields which have lyrics and then recreate it empty... or create another field to keep the lyrics, I realy don't know.

Thank in advance and, please, excuse my not-too-good English.

No problem, just do it.

Mp3tag does not store a tag-field with no content, therefore the tag-field's edit dialog ... "doesn't keep the "OK" button able".
Simply delete the tag-field in the dialog "Extended Tags..." [Alt-T] by pressing the [Del] key resp. by clicking the "Red Cross" button.

There is no customization available for a new window just for unsynced lyrics only.
But you can add a multi-line edit field into the Tag-Panel window in the "Mp3tag Options/Tag-Panel" dialog to display the text from the tag-field UNSYNCEDLYRICS in the Tag-Panel window.
The Tag-Panel window can be placed anywhere on the screen/s where you want it.

You can use the action "Format value" resp. the converter "Tag - Tag" to create a new tag-field with a name of your wish.
So you can copy or move data from one tag-field to another tag-field.
See there ...