The accessibility and usability of various indoor navigation apps and systems based on different modalities and technologies have been investigated in the past. However, most of these studies were based on prototypes developed and evaluated as part of research initiatives. There is a lack of research exploring indoor navigation's usability from the perspective of Blind and Visually Impaired (BVI) users. To address this gap, we conducted two studies: a survey and semi-structured interviews, to gather the preferences of BVI users on improving the usability and features of indoor navigation apps. Findings emphasize users' preferences for external consistency, layout customization, contextual information, and wayfinding abilities in indoor navigation apps. Overall, this study provides initial insights for improving the usability and features of indoor navigation apps through a user-centered approach.