I had the same issue, but the FAQ answers it:
How to click a button with a changing ID (partial ID match)?
On some websites the ID of a button (or an element in general) is changing between different page loads (dynamic ID). This means the test case macro will fail at replay as the button has a new ID after each page refresh.
Solution: Typically some part of the ID remains constant e. g. post-123456 and post-555555. We can use XPath’s starts-with or contains functions to search just for the stable part of the ID. So the selector will be something like this: //*[contains(@id, ‘post-’)].
See here clickAndWait, click - Selenium IDE Commands Tutorial