its very distracting, would be very gratefull for any suggestones can if any one can help  thanks

hi in a new win 10 instal most text incl Fire Fox and t bird text is made up of letters [font] that are made of thin and thick lines [in the same letter] i dont know if its a strange font or another problem, i have copied all "font" setting from my other pc where i dont have the problem. also i cant get spell check to work here dsespite turning it on its very distracting, would be very gratefull for any suggestones can if any one can help thanks