edit tooltip wording

Author: Aiz0

static/locales/en-US.yaml

@@ -771,7 +771,7 @@ Tooltips:
       method for grabbing your subscription feed. RSS is faster and prevents IP blocking,
       but doesn't provide certain information like video duration or live status
     Fetch Automatically: When enabled, FreeTube will automatically fetch
-      your subscription feed on start and when switching profile.
+      your subscription feed when a new window is opened and when switching profile.
   Privacy Settings:
     Remove Video Meta Files: When enabled, FreeTube automatically deletes meta files created during video playback,
       when the watch page is closed.