Youtube embed problem

Hi,I am pretty new to all this so please forgive me if I have posted this in the wrong place.
I have just published my first website using Modx and have been trying to embed my Youtube videos within the site,at first this seemed to be easy,however,while the player is visible and working immediately after adding the embed code,the video player/video dissappears from the page at the next edit.If I look then at the code the embed code is still there but ModX seems to reset the object width/height parameters to "0",thus rendering the player/video invisible on the page.Resetting these parameters brings back the player/video, but when you save the changes the same thing happens again.

Can anyone tell me where I am going wrong here please?

Try turning off Rich Text editing for that page.

Thanks sottwell, for your prompt and accurate reply.
That’s fixed it!

Sometimes those javascript Rich Text editors are just a bit too "helpful"!