Oh hey, I face the same problem with Chinese too 😅
Does the app provide example sentences with the new word you're learning?
I'm not sure what kind of words the app is teaching you, but do take note that sometimes the app might be teaching you words that are rarely used or used more commonly in literature, which may explain why you might be struggling to use it in daily conversations.
I'd suggest you to learn new words by reading English articles that are related to your interest or your work. That way, throughout your day, you can try translating what you think in Chinese into English, which will end up using these new vocabulary you have picked up in these articles.
You can consider mastering one word by learning how to use that word in its base form with prefixes and suffixes.
E.g.
actual, actually, actuality, actualisation, etc...
person, persona, personal, personality, personalisation, etc...
Another important thing to note is that one English word can have multiple meanings. So you may need to look up the dictionary to learn all the alternative meanings so that you will be more likely able to use them in your daily conversations.