Problems changing language code
 

Hello, I'm finding myself with problems changing the language code.
The first update I made ​​in ISO-8859-1 and I had to change the Spanish language to find no problems with special characters. Now I run into the problem that when I insert links appear with strange characters, however if I put the code in UTF-8 language appear to me well. The problem arises when switching to UTF-8 I have to adapt the Spanish language, I do this too well and I see special characters well. Now I have a new problem and I can not see the last activity or replies already posted, or use the Page Manager.
Solution that I can apply to move to UTF-8 and not have problems?

Thanks, greetings.