Hi,
This is a behavior of the WYSIWYG editors I've seen before. It is possible that it works better in newer versions of mojoPortal which has newer versions of the editors, or you may try switching editors, ie if you are using CKeditor, try TinyMCE and see if it works better for you. The editor choice can be set from Site Settings.
Note that we never made any official release with version 2.3.6.8, so you must have a build that someone made from source code in between official releases. Version 2.3.7.0 of mojoPortal is the last version that included updated versions of the editors. A new version of TinyMCE was just released yesterday and will be included in the next release of mojoPortal, I added it in our source code repository this morning.
Hope that helps,
Joe