Ask whether the problem is style or language
The appearance help says the service currently uses a standard subtitle presentation rather than customisable colour, shadow and font settings. That answers a styling question. It does not establish that an English translation exists, or that every programme has the same language choices. Write down what the viewer actually needs before searching for a control.
Inspect the original-language edition
FILMICCA’s language page says foreign-language films are supplied in their original production language with Portuguese subtitles. For a viewer expecting English, enlarging text or changing the app interface would not create a new translation. Check the actual film and edition before choosing it for a household whose preferred reading language differs.
Brazilian Portuguese films have another qualification
The same language help says Brazilian films spoken in Portuguese carry subtitles when available. Do not infer universal captions for those works from the subtitle arrangement on imported films. A missing local-language caption track and an existing Portuguese subtitle displayed in the standard style are different cases.
Make an accessibility enquiry specific
If the supplied style is hard to read, describe the film, device, screen and actual text problem to the provider. Ask about an available suitable edition rather than assuming a hidden colour menu exists. This avoids repeatedly changing system preferences in the expectation that the service promises a styling feature its own help currently excludes.
Questions, answered
Can a colour change add an English subtitle track?
No. Appearance and the supplied translation are separate questions.
Does every Portuguese-language Brazilian film necessarily have captions?
FILMICCA qualifies that availability rather than promising it for every work.