- Sign in to your Google Ads account.
- Click Campaigns.
- Select the campaign you want to edit.
- Click Ad groups.
- Select the appropriate ad group from the list.
- Click the pencil button. in the “Default max. CPC” bid column.
- Enter a new amount.
- Click Save.
For More Information Please Refer: https://support.google.com/google-ads/answer/2470113?hl=en