program sends me back to a translated segment every so often

I am using Studio 2017. While translating a document, every two or three segments the program will take me back to a PREVIOUSLY TRANSLATED AND CONFIRMED  segment (in this case it´s a header) and will automatically select (darken) that text, forcing me to go back to that segment and de-selecting text and then go back to the segment I was translating. I had never had this problem before and it is not only annoying but time consuming.  I proceeded to lock the segment to see if that solved the problem but it did not, it keeps doing it again and again. I wonder if it has anything to do with my settings although I´ve never encountered this problem before. I would really appreciate your help in this matter.  Thank you all and many blessings!

Nayeli