Change history is the record Google Ads keeps of every edit made to an account: what was changed, the old and new values, the date and time, the user who made it and the tool used, such as the web interface, Google Ads Editor, a script or an automatic recommendation. It is the first place to look when results move and nobody can say why.
How change history works
You find it under Change history in the Google Ads menu. It can be viewed for the whole account or filtered to a campaign or ad group, and the date range can be set like any other report. Google keeps changes for up to two years at the time of writing (October 2026).
Each entry lists the item changed, for example a budget, a bid strategy target, a keyword, an ad, a location setting or a conversion action, with the before and after values. You can filter by user, by type of change and by the tool. That last filter matters because many changes are not made by a person at the keyboard. Changes can come from:
- People working in the interface or the mobile app.
- Auto-applied recommendations, which Google makes on your behalf if they are switched on.
- Automated rules and Google Ads scripts.
- Bulk uploads, Google Ads Editor and third-party tools working through the API.
Many changes can be reversed directly from the list with an undo option, which restores the previous value without having to rebuild it by hand.
Why it matters
When cost per lead doubles in a week, the cause is usually one of two things: something changed in the market, or something changed in the account. Change history answers the second question in minutes. A doubled budget, a new broad match keyword, a target CPA lowered too far, or a location setting switched by a recommendation will all show up there.
It also matters for accountability. If several people, a freelancer or an agency have access, the log shows who did what, which helps when an account is handed over or a dispute arises about spend. For any UK business paying someone to manage ads, it is the simplest way to confirm that work billed for was actually carried out. Google Ads also lets you add notes to performance charts, which pairs well with the log.
Common mistakes
- Never checking it until something has gone wrong, by which point several changes overlap and the cause is hard to separate.
- Leaving auto-apply recommendations switched on and not reviewing what Google changed.
- Sharing one login between several people, so the log cannot tell you who did what.
- Judging a bid strategy change within days, without checking change history for other edits made in the same week.
- Undoing a change without understanding why it was made in the first place.
How to act on it
Give every person who works on the account their own login with the right access level, so every entry is attributable. Each week, scan change history filtered to changes made by Google or by automated tools, and decide whether you agree with each one.
When performance shifts, set the date range to cover the week before the shift and read every change in that window before touching anything else. Add a chart note for major edits such as a new bid strategy or a budget change, so you can line them up against results later. A change history review is part of every account audit I do in PPC management, and it often explains problems faster than any performance report.