Cursor in Excel text field is jumping back and forth and degrading text. Why, and how to fix?

System: Mac OS X 10.10.4

Updated to Yosemite about a month ago with no problems

Just recently installed Microsoft Office.

Word is working fine so far.

I have not yet dabbled with Publisher, etc... Just Word and Excel for now.

This question is in regards to the first time that I have tried using Excel on this computer since installing it a few days ago.

I began writing text in Excel, using one or two sentences per cell for roughly 10 cells in a column.

I then went back to make edits. When I tried to put my cursor into the text field (not the cell itself, but the formula field at the top), the cursor would appear to be placed where I wanted it. However, when I type or delete anything, the letters appear or delete a few spaces before the cursor. Further, when I arrow through the text, the cursor seems normal at first, but then begins jumping back and forth around the words as it trends in the general direction of the arrow key I am pushing. Lastly, as the cursor moves through the text, it begins to slowly degrade the text in this field making it harder to read.

If I hit enter, the text normalizes in the cell itself again. However, this makes editing difficult, as the exact number of spaces away from the cursor where letters and deletions take place is difficult to estimate quickly. This problem makes working in excel annoying, as everything takes longer to edit.

I did copy the text and paste it into a new Excel doc, but the problem persisted. I then opened up a new Excel doc and started over writing just one line. When arrowing through, the problem again persisted. Doing a Google search for answers, I saw a lot of vaguely similar problems associated with the Zoom function for Google docs, so I tried tinkering with Zoom, and no such luck there either. I have made adjustments to my background resolution recently, so I tried tinkering with that a little, but that also did not fix the problem.

I do not seem to have text problems with internet browsers, pages, word, or anything else, just with Excel.

I am hoping that there is a quick and simple fix for this. I do not want to download any new software in order to fix this problem unless it is directly from a highly trusted site such as Apple, or Microsoft themselves. A lot of quick download fixes install other problems and I'd just rather not have to hassle with that.

Any help would be appreciated.

Thank you.