I am working on timeseries data of different states. to check if the prices are stationary for each state I am running the dickey fuller test. for estimating models I am running AC and PAC to get AIC and BIC. However, after the first model I am continuously getting same AIC and BIC for all the models. only when if I stop the program and start the program always news then only I get the new values. I understand that software is saving the values. I dont know how should I resolve this problem as clear and drop _all commands are not working.