Adaptive assistive technologies can support the accessibility needs of people with changing abilities by monitoring and adapting to their performance over time. Despite their benefits, these systems can pose privacy threats to users whose data is collected. This issue is amplified by the ambiguity on how user performance data, which might reveal sensitive health data, is used by these applications and whether similar to medical data it is protected from unauthorized sharing with third-parties. In interviews with older adults who experience pointing difficulties, we found that participants felt a lack of agency over their collected pointing data and desired clear communication mechanisms to keep them informed about the privacy characteristics of adaptive assistive systems. Based on this input, we present an icon set, that can be used in online application stores or with the licensing agreements of adaptive systems, to visually communicate privacy characteristics to users.