Your Moving Average may not be using the same scale as your Price Graph. You can change this as follows: Right click the Moving Average line and select Scaling from the menu that appears. Now look at the Price Scale on your chart. Is it on the left of right of the screen? The Scaling Menu for Moving Average will provide scaling options and you want to select a merge choice to merge with your Price Graph scale. For example if your Price Graph scale is on the Right of the screen select Merge with scale and right and click OK. Once the moving average and the price graph are using the same scale the positions should remain the same when you zoom. Note: if this doesn't work it could mean the Smart Chart for this chart is damaged. Replace the Smart Chart as follows: Start MetaStock. Click File | New | Chart. Highlight the troublesome chart and click OK. Plot both Moving Averages in the new chart. If this works it means your original chart is damaged. Continue as follows: Click File | Save As. Click Save As Smart Chart, to place an X this box, and click OK. A message will ask you want to replace your existing Smart Chart. Answer yes. Click File | Close to close this chart. Repeat this procedure for any other chart that does this.