Keyboard (model sk-9621) switching to/from “French” characters

I have an issue with my Keyboard (model sk-9621) which will often suddenly be in “French” character mode and I am sure I have done something to activate that but am unable to get back to the previous mode. It will tend to be in “Standard mode” in one program (such as “Word”) but remain in “French mode” on the internet for example. I would like to better understand how to quickly switch between keyboard modes and to find a chart that shows what the “invisible” characters are in “French mode”. I would prefer not to “disable” the French mode because I would like to be able to use that as well (Multilingual).