"Auto-correct" when editing post

This is my forum: http://gskvn.forumvi.com/
Somehow I have been encountering a weird problem: A simple formatted post can be ruined by simply clicking on "Edit". A formatted text as basic as

Code:

[size=24][color=#FF0000][center]ABCXYZ[/center][/color][/size]

when revised, would somehow turn into

Code:

[center]ABCXYZ[/center]

This problem is annoying, because our users are forced to hesitate whenever they want to edit a formatted post. The problem quickly went from annoying to pure destructive in long and complex post, which has been greatly hindering our effort.
I haven't use any custom script in my forum yet.
As a result, I would like to know whether this problem is about Forumotion or SCEditor or something else? And how it could be solved?
Any help would be appreciated.

Are you switching modes: normal and WYSIWYG?

No I'm not, I keep using normal mode all the time.
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Besides when I write my post in normal mode and press switch button, that problem happend too.

Are you manually adding the BBCode or using the buttons in the editor?  Does this happen in all browsers?

It does look like you are switching the modes, because switching them will remove some formatting.

The problem happend either when I use the button or manually write the code myself.
All I do is write the post, posting it, and when I press the edit button everything is gone.

Do you have the WYSIWYG mode set to default?  If you do, do you switch to normal mode before posting a post or editing a post?

No, the default mode in the editor is normal mode. And when I post or edit a post its mode is normal mode, too.
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I have try another type of format, and I figured out that the problem only happend when "center" tag is inside another tag. For example:

Code:

[b][size=18][color=#ff0000][center]abcdee[/center][/color][/size][/b]

This will cause the problem to happend, which remove all tags and only the center tag is left.

Code:

[center]abcdee[/center]

but if I move the center tag outside other tags, it will work normally in both mode, and no problem happend when I switch editor mode when write the post

Code:

[center][b][size=18][color=#ff0000]abcdee[/color][/size][/b][/center]

I just remembered that it does matter the order of the BBCode tags.

Yeah... But it seems that this forum dont have this problem at all, its display normally no matter what order I use, is there a difference in the two forums?
Is there a solution at the "universal" level, that does not involve making every user remember the correct order of tags?

The reason this occurs is because the SCEditor is attempting to correct your tag placement. The color and size tags are inline elements, and the center tag is a block-level element. Inline elements cannot contain block-level elements, hence the hackish correction. I'd recommend installing the following script from the tutorial below on your forum to override these corrections, because they're more bothersome than helpful.

https://help.forumotion.com/t135105-correct-the-formatting-of-the-new-editor-in-source-code-mode

That is exactly what I needed. Thank you very much!
My problem is solved.