Time Comments Font-Firestick

Is there a way to change the font size and color on a drama while using firestick? I was able to change my subtitle color through settings but there is no option to change timed comments . Right now they are in white along the top of tv screen which is now not very visible. I went out and bought a new laptop Bluetooth, which is not connecting well so and my current tv location  don’t allow me to add the hdmi cable directly as I did before in a old laptop due to location of tv now.  I went out and bought Firestick just so I can have the timed comments option . Without timed comments availability and lack of setting I really cannot get into the dramas as much. If that’s the case I may as well discontinue plus membership n go to other streaming service I get for free, through various sources and would not pay for streaming service other than VIKI. I have not been able to watch my drama since November due to lack of devices that support timed comments other than my small mobile devices which I do not like watching dramas on. Please consider adjustments to the items indicated along with expanding the time comments option. I bought Roku stick when I first got tv only to find out it does not support timed comments. Hence the recent  firestick purchase now but it still does not user friendly.

Thanks in advance