I emerged the kde-3.2.0 with the ACCEPT_KEYWORDS=~x86 emerge blabla well but when i make an emerge -UDp world or Up world portage wants to emerge kde-3.1.5 (again)
That's the way portage works - they're slotted separately. If you want to prevent it, either unmerge the 3.1 version or use some or look up in the forums/docs how to setup portage's configuration files to prevent this.
yeah i have tried umerging kde-3.1.5 but portage wants it again because the new k3b , and i tried too removing the kde entries in the world file but again the k3b wants the kde-3.1.5, maybe is an ebuild problem?
No, it's not an ebuild problem. The kde 3.2 packages are still marked as ~unstable. It's your choice to use them with the ACCEPT_KEYWORDS, but until they become x86 stable portage will want to upgrade the 3.1 series. You can configure portage to circumvent this behavior. See the manpage for portage, and look for the package.keywords file.