I installed a new version of TortoiseSVN, but the new functions aren't visible

TortoiseSVN is a Windows explorer shell extension. So after updating you must restart windows or at least the explorer process. If you don't then the the explorer process still has the old version of the dll loaded in RAM and uses that old version...

If that doesn't help, uninstall TortoiseSVN again. Then run our little CleanInstall tool you can download from here. Then you can install TortoiseSVN again.