I can't change my subtitles settings from srt files

[PEDRO5CC2]

I'm using Premiere 2019 (13.1.5) and I'm having trouble changing my subtitles settings for my.srt files. 
After doing the dowloand of the files using the Kapwing website / app, I try to make changes such as changing the color of the legend, changing the formatting of the legend line or removing the black background from the subtitle. 
Sometimes Premiere let me make some changes and sometimes it doesn't, being completely random when it lets me change it or not. 
Does anyone know how to solve this or some way to download subtitles for videos in a quickly way, like using Kapwing, but without having this problem of sometimes not being able to change the file settings?

[Richard van den Boogaard]

SRT typically is a basic text type of subtitle, meaning it is not designed to handle different fonts or formattting.

[Stan Jones]

I'm not sure whether you are trying to change the formatting when importing the srt, or to change formatting after you have imported. Either one should work for Open Captions. If you are working with closed captions, you will be limited if you try to make changes after importing.

Before import, in the Captions Panel, click on the Import Settings button. Select the "Import File type" as srt. Click the check box for the appropriate section(s) and make your settings.

If after import, what type of caption stream are you using?

Stan