Hi was wondering if anyone could help me. I'm not sure what I'm doing wrong? But in light room if I'm editing a photo the edits I add are already done, but if I go to add a preset, or want to put one on those edits that were previously done completely disappear and no longer exist on the photo? Which is hard because if I want to brighten the color of something, and then add a type of saturation preset the brightness I did previously is gone? I'm not sure if it's supposed to do that? But other colleagues of mine do not have the same problem I do? Thank you for the help I appreciate it.
Yes, a Preset will over-ride any adjustments made IF the Preset includes a different value for the same adjustment.
eg. You have changed Exposure to +2 and applied a Preset that includes [Exposure +1], the final result will be [Exposure +1]
For 'third-party' Presets that may include many adjustments, you may be better applying the Preset first, then modifying your adjustments.
When creating your own Presets- you only need to [check] the adjustment/s you want applied in the Preset creation dialog. eg. if your Preset only has [Saturation] checked, then it will not affect any other previous edit adjustments.
Jared Platt in his blog has a video that describes how to create a Preset for a B&W image-