Twitter users, even if they have several accounts installed in their mobile application, when they are going to perform an action, whatever it is, it is done with the account in which they are currently active. That is, any comments will be automatically published with that account they are in, without the possibility of choosing.
However, this may change in the coming weeks, since Twitter is testing functionality that will allow users to choose which account they want to respond to when they respond to a tweet.
This has been reported by some users, who are being tested by the social network to see if this functionality would be successful. When you go to answer a message, Twitter will display a message that indicates which account you want to respond to, and will allow you to choose another.
This is something that other social networks already allow. For example, Facebook allows you to choose whether to reply to a publication with the personal profile or with that of the corporate page that is managed. This, for the moment, on Twitter is not possible.
At the moment there is no official confirmation by Twitter that the functionality will be officially launched or if, on doing so, on what date it would. Anyway, it seems logical that it is finally implemented, more taking into account that it is a function that if available on TweetDeck, the cross-platform social media manager that is owned by Twitter. In fact, the company periodically adds some functions included in its manager to the social network.
The new function could be useful for those people who have several accounts installed in your application, but it will also imply the need for an extra verification exercise, since it could be more difficult to make a mistake when responding and do it with an account that was not the one wanted to.