We recommend to only activate the theme editor when you possess sufficient knowledge of HTML and CSS.
When you activate the theme editor, you will no longer receive theme updates. If for example, Lightspeed eCom provides an update for a given theme, the update code is added to the main theme code, as it resides on our servers. Connected to that main theme are all online stores that have it installed. Whenever the main theme is updated, the update will also be implemented across all connected stores.
However, if you activate the theme editor, your online store will be disconnected from the given main theme and regarded as having a custom theme. If Lightspeed eCom updates the main version, it will not implemented in your store. You will receive the settings associated with the update and be able to see them in your back office, but it will not have any visible effects in the front end of your online store. To achieve this, you will have to manually place the update code in the back office. We usually provide update codes through our blog or forum.
A example from the past was the blog function. It was issued as a system update. Online stores that had already activated the theme editor beforehand, could see the blog listed in the left menu of the back office but not in their front end, because the required blog code was missing.