There are two major rules that govern tense changes in reported statements.

1- PRESENT--------------------> PAST

2- PAST-------------------------> PAST PERFECT

Consider the following examples:

Anna said:" I eat an ice cream"Anna said that she ate an ice cream

Anna said:" I am eating an ice cream"

Anna said that she was eating an ice cream. Anna said: I have eaten an ice creamAnna said that she had eaten an ice cream

Anna said:" I have been eating an ice cream"

Anna said that she had been eating an ice cream.

Anna said:" I ate an ice cream"

Anna said that she had eaten an ice cream

Anna said:" I was eating an ice cream"

Anna said that she had been eating an ice cream

Anna said:" I had eaten an ice cream"

Anna said that she had eaten an ice cream.

NB: Past perfect and its variations do not change

Anna said:"I had been eating an ice cream"

Anna said that she had been eating an ice cream Anna said :" I will eat an ice cream"

Anna said that she would eat an ice cream

Anna said :" I will be eating an ice cream"

Anna said that she would be eating an ice cream

Anna said:" I will have eaten an ice cream"

Anna said that she would have eaten an ice cream

Anna said:" I will have been eating an ice cream"

Anna said that she would have been eating an ice cream

Major changesPersonal pronouns

I

You

He

She

It

We

You

theyHe/she

I /He/she

~~

~

TheyWe/they they

upon moving from direct to indirect speechPossessive adjectives

My

Your

His

Her

Its

Our

Your

theirHis/her

My/ His/her

~~

~

Their

our/their

~

Possessive pronouns

Mine

Yours

His

Hers

Its

Ours

Yours

theirsHis/hers

Mine/His/hers

~

~

~

Theirs

Ours/theirs~

Adverbs of time ,place & demonstratives

Now

At this moment

Todaytonight

Tomorrow

NEXT (week, month, year...)

Yesterday

Ago

Last (year, month, week...)

HereThereThisThat

TheseThose Then / at that time

At that moment

That day

That night

The next day / the following day

the (week, month, year...) AFTER

the following(week, month, year...)

The day before/ the previous dayBefore

THE (year, month , week...) BEFORE

THE PREVIOUS (year, month, week...)

There~

That

~

Those~

Modals

Will

Shall

May

Must

Have to

Can

Should

Could

Would

might

Ought toWould

Would

Might

Had to

Had to

Could

~

~

~

~

~

PRESENT TENSES

PRESENT--------------------> PAST

PAST TENSES

PAST--------------------> PAST PERFECT

FUTURE TENSES

WILL--------------------> PAST FORM (WOULD)